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Controlled nanoarchitectures for the effective storage of hydrogen
Francois Aguey-Zinsou
MERLin Group, School of Chemical Engineering, The University of New South Wales, Sydney, Australia,
Storing hydrogen in materials is based on the observation that metals can reversibly absorb
hydrogen, however practical application of such a finding has found to be rather challenging
especially for vehicular applications. The ideal material should reversibly store a significant amount
of hydrogen under moderate conditions of pressures and temperatures. To date, such a material does
not exist and the high expectations of achieving the scientific discovery of a suitable material
simultaneously with engineering innovations are out of reach. Of course, major breakthroughs have
been achieved in the field, but the most promising materials still bind hydrogen too strongly and often
suffer from poor hydrogen kinetics and/or lack of reversibility. Clearly, new approaches have to be
explored, and the knowledge gained with high-energy ball milling needs to be exploited, i.e. particle
size does matter! The properties of nanomaterials are known to be size depend. Such size depend
effects could offer powerful means to finally control both the thermodynamic and kinetic properties of
hydride materials at the molecular level.
Here, the potential of this new approach1
as well as the major breakthroughs achieved through
nanosizing will be discussed. In particular, the effects of particle size restriction on some of the most
promising hydrogen storage materials, i.e. magnesium and borohydrides, will be reported. Hence,
through particle size restriction full desorption of hydrogen, i.e. 7.6 mass % of hydrogen, was
achieved at 85 °C with colloidal magnesium1 instead of the usual 400 C required for bulk
magnesium. Similarly, core-shell NaBH4@Ni nanoparticles demonstrated for the first time the
possibility of reversibly storing hydrogen under practical conditions with NaBH4,2 a compound that
irreversibly decomposes into its elements at temperatures > 500 C.
.
1Aguey-Zinsou, K.F.; Ares Fernandez, J.R. (2010): Energy Environ. Sci. 3 (5), 526-543.
2Christian, M.; Aguey-Zinsou, K.F., (2012): ACS Nano, 6(9), 7739-7751.
2
Effect of the Different Amino Acid Hydrophilic Head in the
Adsorption Behavior of Eco-Friendly Glycerol Ether Surfactants at the
W/A Interface
C.D. Ampatzidis, E-M. A. Varka and T.D. Karapantsios
Dept. Chemistry, Aristotle University of Thessaloniki, [email protected]
Environmentally friendly surfactants are gaining ground in the last decades. Thus, two novel
nonconventional biocompatible and biodegradable glycerol ether surfactants were synthesized. Both
molecules have a hydrophobic alkyl chain with 12 carbon atoms, but different amino acids in the
hydrophilic head: phenylalanine (PhGE12) and tyrosine (TyrGE12). The TyrGE12 molecule has a
phenolic group, viz. a benzene ring with a hydroxyl, instead of a simple benzene ring in PhGE12
Measurements of dynamic surface tension by maximum bubble pressure tensiometry and drop profile
tensiometry are carried out for alkali aqueous solutions over a wide concentration range and for
surface ages spanning from milliseconds to hours. CMC values, standard free energies of adsorption
and other physicochemical properties are calculated based on static (equilibrium) surface tension
measurements. Interfacial dilatational storage modulus and loss modulus measurements have also
been conducted. It is found that TyrGE12 not only reduces surface tension to much lower values than
PhGE12 but it also exhibits much faster interfacial adsorption than PhGE12. Thus, different polar heads
in glycerol ether surfactants can give appreciable differences to adsorption kinetics comparable to
effects commonly expected for surfactants with different alkyl chain length.
3
Effect of fluid properties on gas-sheared and free interfaces
N. Andritsos, V. Bontozoglou, M. Vlachogiannis, A. Georgantaki, Z. Cao
Department of Mechanical Engineering, University of Thessaly, 38334 Volos, Greece, [email protected]
The laboratory of Transport Processes at UTh has placed a strong interest in examining
phenomena of flows with free surfaces/interfaces or with gas-liquid interfaces in pipes and channels.
The interaction between a gas and a liquid phase moving concurrently in a conduit has been
the subject of intense research in the last several decades, due mainly to the importance of such flows
in the chemical, nuclear and petroleum industry. Although the flow characteristics such as liquid
holdup and pressure drop have been extensively studied, our understanding is still limited regarding
the effect of several physical properties of the two phases. The experiments were conducted in a 24-
mm i.d., 13-m long transparent pipe at atmospheric pressure. Horizontal and near horizontal (±2º)
flows were examined. The physical properties that have been investigated or are being investigated
are gas density (by using CO2 and He), liquid viscosity (glycerol solutions), surface tension (n-butanol
and isopropanol solutions) and drag reducing polymers.
Liquid film flows occur in a variety of geophysical and biological situations, and are of central
importance in many industrial applications, such as heat/mass transfer equipment and coating
processes. The present experiments were performed in two inclined flow facilities of adjustable width,
one 800-mm long and 250-mm wide and the other 3000-mm long and 450-mm wide. Inclination
angles in the range θ = 2–45◦ were tested for flat and for periodically corrugated substrates, and the
liquids examined were aqueous solutions of glycerol, of isopropanol and of SDS surfactant. The
research focused on the modifications of the primary instability of steady flow. It was shown that
finite channel width has a significant stabilizing effect, which may be satisfactory correlated in terms
of the Kapitsa number and is attributed to three-dimensional effects imposed by the side-walls.
Corrugated substrates were shown to have an enormous potential in modifying the characteristics of
the flow, prominent among which is the transition from the classical long-wave to a short-wave
instability. Finally, soluble surfactants were observed to provide maximum stabilization at
concentrations only a few percent of the critical micelle concentration.
4
Decomposition of MgH2 films investigated by Ion beam techniques
J.R Ares, I.J. Ferrer, J.F. Fernández, C. Sánchez
1 MIRE group, Dpto. Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain
Magnesium has been a material widely investigated to store hydrogen1 because of its cheapness
and high gravimetric capacity. However, despite the enormous amount work done, certain problems
(high stability and sluggish H-kinetics) continue to preclude its use for transport purposes. In this
context, MgH2 films are an excellent tool to investigate the influence of microstructure or/and the
surface state on H-absorption/desorption steps (H2-dissociation, H-diffusion, ect) and films could be
also used in other applications such as the switchable mirrors or H-detectors.
Different techniques have been used to characterize the H-desorption process of Pd-capped
MgH2 films i.e. Glancing-XRD (G-XRD), SEM-FEG, optical and transport measurements, mass-
spectrometry, calorimetry. Ion beam techniques (IBT) offers a complementary approach2,3
to
investigate the desorption process giving detailed compositional depth profiles of the films. Among
the different available IBT, Rutherford Backscattering (RBS) and Elastic Recoil Detection Analysis
(ERDA) were used to determinate the profiles of Mg and Pd as well as hydrogen in the films.
In this work, Mg films of nominal thickness of 300 nm were prepared by e-beam deposition
and capped by a 10 nm layer of palladium. Hydrogenation of films was carried out at 100 ºC and 10
b during 20 hours. Hydride films were structurally characterized by G-XRD and FEG. They exhibit
MgH2-crystallites with sizes of 80 ± 30 nm and film thicknesses of 380 ± 20 nm. Thermal desorption
was investigated by Mass Spectrometry and "in situ" optical measurements.
MgH2 films were analysed in detail by RBS and ERDA techniques at different stages during the
desorption process. Those results show the evolution of H, Mg and Pd depth profiles in the film
during H-desorption. According to obtained data, a brief discussion about the desorption mechanism
and the formation and influence of Mg-Pd phases or/and intermixed layer will be given.
1 Aguey-Zinsou F.K., Ares-Fernandez J.R., (2010): Hydrogen in magnesium: New perspectives to functional stores. Energy
and Environmental Science 3, 523-546
2 Ares, J.R.., Leardini, F., Diaz-Chao, P., Bodega J., Koon D.W., Ferrer I.J., Fernández J.F., Sánchez C. (2010): Hydrogen
desorption in nanocrystalline films at Room temperature. J. Alloys Compd. 495, 650-654.
3Gautam, Y.K.., Chawla, A.K.., Khan, S.A.., Agrawal R.D., Chandra R. (2012): Hydrogen absorption and optical properties
of Pd/Mg thin films prepared by DC magnetron sputtering. Int. J. Hydrogen Energy 37, 3772-3778.
5
Endoscopic digital holography for application in biomedical flows
Laura A. Arévalo, Virginia Palero, Mª Pilar Arroyo
1 Instituto de Investigación en Ingeniería de Aragón (I3A), Universidad de Zaragoza, Zaragoza, Spain,
Several approaches for the combination of optical metrology with endoscopes have already
been reported1,2
. On one side, interferometric based techniques have been used for studying the
behaviour of cavities both in the medical and in the industrial field. Solid mechanics information
(shape, deformation, vibration,…) is obtained and no fluid mechanics is involved in the process. On
the other hand, endoscopic PIV has been developed to measure velocity fields on difficult access
flows. In this case, the endoscope is used only for illumination while the recording is done through a
transparent window.
Our objective is to simultaneously obtain both fluid mechanics (flow velocity field) and solid
mechanics (wall deformation) information3. We propose to combine endoscopic illumination and
imaging with digital holography recording. The reconstructed phase should provide information on
the wall deformations while the reconstructed intensity should allow calculating the velocity field.
The final goal for the proposed technique is to be used for measuring the fluid-structure interaction in
real blood vessels in ex-vivo experiments. This interaction is expected to be related to cardiovascular
diseases like atherosclerosis and aneurysms and thus useful information about them could be inferred.
(a)
(b)
(c)
Figure1. a) Endoscopic digital holography setup. Sketch of the off-axis digital holography setup
Preliminary results for: b) the flow velocity field inside the vessel; b) the vessel wall deformation.
1 Schedin,S., Pedrini, G., Tiziani, H.J., Aggarwal, A.K. (2001): Comparative study of various endoscopes for pulsed digital
holographic interferometry. Applied Optics 40(16), 2692-2697.
2 Schnars, U., Jueptner, W. (2005): Digital Holography. Digital hologram recording, numerical reconstruction and related
techniques". Berlin: Springer.
2 Arévalo, L.A., Palero, V.R., Lobera J., Arroyo, M. P., (2012): Endoscopic digital holography for measuring flows in
opaque vessels, Proc. SPIE 8413; doi: 10.1117/12.977946
6
On the “very stable” aqueous foams
Laura Arriaga, Wiebke Drenckhan, Emmanuelle Rio, Anniina Salonen, Dominique Langevin
Laboratoire de Physique des Solides, CNRS- Université Paris Sud 11, Orsay, France, [email protected]
Aqueous foams destabilise through different mechanisms: gravity-driven drainage, leading to
thinning of films between bubbles, coalescence of bubbles and Ostwald ripening (gas transfer
between bubbles). We have shown recently that foams stabilised by partially hydrophobic silica
nanoparticles experience drainage, but are fully stable against ripening and coalescence: these foams
are “ultrastable”1. A similar behavior was observed by Stoyanov and coworkers for foams stabilized
by a protein, hydrophobin2. We discuss here the case of foams that are much more stable than
classical surfactant foams, but that nevertheless destabilise after long times (days) : these are foams
stabilized by mixtures of anionic and cationic surfactants (catanionics)3 and by mixtures of
hydrophilic silica nanoparticles and short chain amines4. In these cases, drainage is slowed down by
bulk aggregates thatcompact in the Plateau borders (junctions between foam films), but ripening and
coalescence are not suppressed, they are slowed down due to the rigidity of the surface layer. The
difference in behavior between these very stable foams and the ultrastable ones will be discussed.
1 A. Stocco, E. Rio, B.P. Binks and D. Langevin (2011) Aqueous foams stabilized solely by particles” Soft Matter, 7, 1260
2 K. D. Danov, G. M. Radulova, P. A. Kralchevsky, K. Golemanov and S. D. Stoyanov (2012) Surface shear rheology of
hydrophobin adsorption layers: laws of viscoelastic behaviour with applications to long-term foam stability Faraday
Discuss., 158, 1–27 3 L. R. Arriaga, D. Varade, D. Carriere, E. Rio, W. Drenckhan and D. Langevin : Surface rheology of catanionic layers
adsorbed from solid-like vesicles and their role on foam stability Soft glassy nature of catanionic films and their role on
foam stability, Langmuir, submitted 4 L. R. Arriaga, W. Drenckhan, A. Salonen, J. Rodrigues, R. Íñiguez-Palomares, E. Rio and D. Langevin : On the long-term
stability of foams stabilised by mixtures of nano-particles and oppositely charged short chain surfactants Soft Matter,
accepted
7
Quest for new detection limits in green and smart interface
measurements
Kevin Arthure2, Nick Barnett
5, David Creasey
5, Leo Creedon
3, James Egan
6, Norman McMillan
1,
Fionn Murtagh4, Martina O’Neill
2, Philippe Pringuet
6, Sven Riedel
2, Stephen RP Smith
2
1 Drop Technology Ltd., Whitestown Business Park, Tallaght, Dublin 24, Ireland: [email protected]
2 Drop Technology Ltd., Whitestown Business Park, Tallaght, Dublin, Ireland 24
3 School of Engineering, Sligo Institute of Technology, Co. Sligo, Ireland
4 Department of Computer Science, Royal Holloway, University of London, Egham Hill, Egham TW20 0EX, London, UK
5 Ocean Optics, St Clements Business Centre, 1-5 London Place, Oxford, OX41BD
6 Bahrain Polytechnic, PO Box 33349, Isa Town, Kingdom of Bahrain
There are important metrological issues involved in pushing the limits in both drops and bubble
measurements requiring a general reappraisal of specifics in what might be at first sight be considered
to be overarching chemical issues. Currie1 as the chair of the international committee (IUPAC) started
to look afresh at long established conventions on limits of detection and limits of quantitations (LO-
D&Q). This work is of central importance to metrology and in large part represent the thoughts of the
IUPAC; surprisingly this work is not based on rethinking the important metrological issues from
statistical fundamentals in determining the LO-D&Q. This determination requires a strict criteria in
the formulation of a detection decision by means of a properly defined statistical test. The rigorous
statistical survey of such a test method by Liteanu and Rîcă2 properly addresses this measurement
issue and their work is being applied in the research for Drop Technology spectroscopic products.
These issues are considered to be very hard work and indeed somewhat of a distraction to many
research personnel, whereas for surface science non-collimated spectroscopy (NCS) they are at the
core considerations. Here an attempt in revolutionizing the approach to UV-visible measurements is
proposed. NCS is clearly a departure in surface science and both bulk and surface spectra of the drop-
under-test (DUT) are obtainable on a complex solute offering new measurement possibilities; real
time differential analysis have obvious important applications in biochemistry, medical/veterinary and
environmental science. The NCS requires a range of measurement protocols to be established that are
based on a new surface science which bypass the limitations of the collimated Beer’s Law approach
of traditional spectroscopy. This new drop science requires that measurement protocols are reframed3.
The basis of this new quantitative approach illustrates how smart surface science can break through
the established protocols and this paper will seek to demonstrate the importance of accuracy and
traceability in NCS measurements with NIST standard. Furthermore, a full range of quantitations in
these measurements can be delivered to the analyst to assist them develop smart ‘flexible and
optimized’ approaches to measurement that make statistics a live component in laboratory work and
not an after-thought that it has unfortunately so often been. This new approach begs the question of
using information theory in a more dynamic way that heretofore can be exploited to build an
improved measurement platform for smart chemistry and biology. This vital issue is discussed in a
general way extrapolating from the specifics of NCS to smart and green surface science in a general
way. It is argued that the exact Laplace mathematics defining shapes of drops, bubbles and the
meniscus when coupled with advanced numerical methods of computer modeling techniques for
optics when applied in the context of best statistical methods can deliver a revolution in spectroscopy.
8
LiFePO4 cathode – electrolyte interface in lithium ion batteries
G.Bajars, G.Kucinskis, K.Bikova, J.Kleperis
Department of Semiconductor Materials, Institute of Solid State Physics, University of Latvia, Riga, Latvia,
With the increasing demand for improved energy storage technologies, the research in lithium
ion battery technology is becoming more and more important. In this work LiFePO4 cathode –
electrolyte interface was studied, focusing on the surface of the cathode for LiFePO4/C and
LiFePO4/C/graphene bulk material and LiFePO4 thin films. The increase of cathode surface area can
improve the rate performance of the cell considerably, thus enable to achieve faster battery charge and
discharge times.
LiFePO4/C and LiFePO4/graphene bulk material have been prepared via solid-state reaction.
After structural and morphological characterization via X-ray diffraction analysis and scanning
electron microscopy an electrochemical test cell with LiFePO4 anode, metallic lithium cathode and
LiPF6 electrolyte was assembled. LiFePO4 thin films have been acquired via radio frequency
magnetron sputtering.
The electrode – electrolyte interface has been characterized with electrochemical impedance
spectroscopy (EIS), determining charge transfer resistance and electric double-layer capacity along
with lithium ion diffusion coefficients. It was found that graphene additive increases not only the
electron conductivity of the material, but also electrical double layer capacitance, thus indicating
larger electrode surface area.
It was found that annealing LiFePO4 thin films promotes grain growth and crystallization, thus
improving charge capacity and rate capability. Charge transfer resistance, electrical double layer
capacity and lithium ion diffusion coefficients have been determined at various charge and discharge
rates. It was determined that charge transfer resistance is smallest at the equilibrium state (3.4 V
potential) with electrical double layer capacitance being significantly lower for thin films than for
bulk materials.
9
Deposits from evaporating droplets
Kyle Baldwin1,2
, Yohana Msambwa1, Fouzia Ouali
1, David Fairhurst
1
1 Department of Physics and Mathematics, Nottingham Trent University, Nottingham, NG11 8NS, UK,
[email protected] 2 Department of Physics, The University of Nottingham, Nottingham, NG7 2RD
As suspension droplets lose their solvent through evaporation, the particles left behind are
deposited into distinctive “dry out” patterns on the surface. Although uncontrolled experiments are
simple to perform, there are many parameters to consider and making a priori predictions for the
shape of these patterns is difficult. Competing effects occur simultaneously and influence the dry-out
pattern: a pinned contact line leads to radial solvent flow and formation of the familiar ring-stain;
spatial variations in surface tension across the droplet (due to either temperature or concentration
gradients) produce Marangoni flow which can redistribute the particles; phase changes within the
liquid (e.g gelation, vitrification or crystallization) and external fields (gravitation, electrostatic,
magnetic) alter the droplet shape and influence the dry out pattern; changing the evaporation rate
alters the relative importance of sedimentation, particle diffusion and heat diffusion…
I will present experimental results from drying droplets of particle suspensions and polymer
solutions which highlight some of these effects. Dilute particle suspensions typically form ring-stains,
the dimensions of which are found to be robustly predicted by established scaling laws over a wide
range of experimental parameters: particle size, concentration, orientation and drying rate. By
contrast, the dry out patterns from polymer solutions are seen to be sensitively dependent on the
underlying phase behaviour of the polymer, with significant differences observed between semi-
crystalline and glass-forming polymers.
10
The Phypode Project, new advances in Physiopathology of Diving
Costantino Balestra1,2
, Virginie Papadopoulou3,1
, Giovanni Distefano4, Giorgi Popov
4, Francois
Guerrero5
1 Environmental & Occupational Physiology Lab. Haute Ecole Paul Henri Spaak, Brussels, Belgium, [email protected]
2 DAN Europe Research Division, Belgium 3 Department of Bioengineering, Imperial College London, London, UK
4 Mares , S.p.A., Rapallo, Province of Genoa, Italy 5 Orphy Laboratory, Universite de Bretagne Occidentale, Brest, France
Funded by the European Union under the Marie Curie Initial Training Networks initiative,
PHYPODE (physiopathology of decompression) is a 4 year project dedicated to the fostering of
bubble/diving/oxygen related research by means of a training consortium to build up the future
researchers in the field.
This up-to-date integrative and translational approach unites 13 teams with complementary
competences from research institutions, industry and clinical practice and supports 14 fellows.
The mechanisms behind the decompression induced formation and growth of intravascular
bubbles that can lead to decompression sickness (DCS) are investigated from an epidemiological and
physiological approach, using the development of technological devices. It combines Human, Animal,
Cellular and Ultracellular Biology as well as Fundamental Physics, Mathematical Modeling and
Industrial device development.
The main structure of the program will be briefly presenting, before concentrating on the new
results obtained thus far in terms of risk factors and preconditioning, focusing on the effect of
vibrating 1 or heating
2 the diver before the dive on the bubble formation observed postdive.
1 Germonpré, P., Pontier, J.-M., Gempp, E., Blatteau, J.-E., Deneweth, S., Lafère, P., Marroni, A., Balestra, C. (2009); Pre-
dive vibration effect on bubble formation after a 30-m dive requiring a decompression stop. Aviat Space Environ Med 80:
12, 1044-1048
2 Gempp, E., Blatteau, J.-E., Pontier, J.-M., Balestra, C., Louge, P. (2008) ; Preventive Effect Of Pre-Dive Hydration On
Bubble Formation In Divers. Br J Sports Med 43:224-228
11
Flocculation of bacterial suspensions using polyelectrolytes
Sandor Barany
Institute of Chemistry, University of Miskolc, Miskolc-Egyetemvaros, Hungary, [email protected]
and II. Rakoczi Ferenc Hungarian Institute, Beregovo, Transcarpathia, Ukraine
Flocculation by polyelectrolytes (PE) is an alternative method for concentration of cellular
suspensions, separation and de-watering of biomasses, etc. We have studied the kinetics, laws and
mechanisms of flocculation of E. Coil and B. Thuringiensis israelensis bacteria suspensions (the
latter is increasingly used as ecologically friendly anti-mosquito agent) by cationic and/or anionic
polyelectrolytes, as well as polyelectrolyte-surfactant mixtures. It has been shown that B.
Thuringiensis suspensions can be efficiently flocculated both by cationic and anionic PE, the
flocculation activity of polymers can be enhanced (a) if the polymer solution is added to the
suspension in two portions, (b) by using polyelectrolyte-oppositely charged surfactant mixtures, and
(c) increasing the cell numbers in the system. E. Coli suspensions can be efficiency flocculated only
using cationic polyelectrolytes. The influence of molecular mass and hydrodynamic dimensions of
macromolecules, their charge density and hydrophobicity, pH and ionic strength of the solution, the
composition of the medium on the efficiency of flocculation of cells has been determined. Also is
shown that for flexible cationic macromolecules, the isoelectric point (IEP) of the cell surfaces is
reached at the minimum suspension stability (neutralization mechanism of flocculation), whereas the
IEP of suspensions in the presence or rigid-chain polyelectrolytes (chitozan and its derivatives) is
reached at much higher concentrations that corresponds to the optimum flocculation. Examples on the
efficient phase separation in bacterial suspensions using polyelectrolytes, their binary mixtures and
mixtures with surfactants are given.
12
Alcohol - water mixtures on hydrophobic surfaces
Pavlína Basařová, Tereza Váchová, Zuzana Brabcová, Nela Korbelíková
Department of Chemical Engineering, Institute of Chemical Technology Prague, Prague, Czech Rep.,
Alcohols along with surface active agents (surfactants) are used in many industrial
applications. Aqueous solutions of alcohols or mixtures of alcohols and surfactants exhibit lower
surface tension and therefore they influence the wettability of solid surface. Due to the development
of new materials and their surfaces, the wettability or nonwettability is a very important material
property. These materials are developed as hydrophobic, but a small addition of alcohol or surfactant
could change the hydrophobicity into the hydrophilicity. Mixtures of water, alcohols, surfactants and
oils are also used for production of micro emulsions. Here, alcohols are used both in low
concentrations (as co-surfactants) and in high concentrations (co-solvents). The systems consisting of
alcohols and surfactants are studied with a high impact on critical micellar concentration,
concentration of alcohols in micelles and bulk liquid, micellar dynamics etc. Together with this
research, the study of internal structure of aqueous alcohol mixtures is going on. Hydrogen bonding
liquids, such as alcohols, have a rich microstructure that the stronger hydrogen bonding water does
not seem to possess. It is found that simple alcohols are micro heterogeneous, since they tend to
develop distinct local microstructures, which depend on the geometry of the constitutive molecule, as
chainlike structures or micelle like structures. This project was focused on the experimental study of
wettability of two hydrophobic surfaces (silanized glass and Teflon) using aqueous solutions of
methanol, ethanol and n-propanol in full concentration range. The surface energy of both tested
materials was examined using Zisman’s method. The surface tension of liquids and contact angles
were measured. For comparison, wettability of one anionic surfactant was studied too. Based on the
experimental data and detailed research study of the internal structure of aqueous solutions of
alcohols, we tend to claim that the dominant factor influencing the surface wettability of alcohol-
water mixtures on hydrophobic surfaces is the presence of microstructures in these solutions. These
mixtures have a higher contact angle when compared with a pure liquid having the same surface
tension (Fig. 1).
Fig. 1 Drop of aniline (A) and propanol solution 8.1% (B) on silanized glass.
13
Study of the three-phase contact line expansion during stationary and
dynamic experimental arrangement
Pavlína Basařová, Tereza Váchová, Zuzana Brabcová, Michal Seifert
Department of Chemical Engineering, Institute of Chemical Technology Prague, Prague, Czech Rep.,
The bubble attachment onto a collecting surface is a common natural phenomenon and the
bubble-particle interactions are used in many industrial applications. The adhesion process is usually
divided into three independent steps – thinning of the liquid film between the bubble and the particle,
rupture of the liquid film and expansion of the three phase contact (TPC) line. The aim of this project
is to study the bubble adhesion on a horizontal plane with a special focus on the TPC line expansion
under different experimental arrangements. The moving bubble (diameter up to 1 mm, Fig 1A) and
stationary bubble (attached on the capillary, Fig 1B) are considered here. Measurements are provided
in pure water; therefore the mobile bubble surface was considered. The adhesion process is recorded
using the high-speed digital camera and bubble parameters (TPC diameter, contact angle) are
evaluated using the image analysis software. The hydrodynamic and molecular-kinetic models1,2
are
used for the mathematical description and parameters of these models are compared for both types of
experimental arrangement.
Fig. 1 Buble adhesion during dynamic (A) and stationary (B) experimental arrangement.
1 Phan Ch.M., Nguyen A.V., Evans G.M. (2003): Assessment of Hydrodynamic and Molecular-Kinetic Models Applied to
the Motion of the Dewetting Contact Line between a Small Bubble and a Solid Surface. Langmuir 19,6796–6801.
2 Phan Ch.M., Nguyen A.V., Evans G.M. (2006): Combining hydrodynamics and molecular kinetics to predict dewetting
between a small bubble and a solid surface. Journal of Colloid and Interface Science 296, 669–676.
14
Energy density enhancement of AC/AC capacitors in aqueous electrolyte
through hydrogen storage in the negative electrode
François Béguin, Elzbieta Frackowiak
Institute of Chemistry and Technical Electrochemistry, Poznan University of Technology,
Piotrowo 3, 60-965 Poznan, Poland
Supercapacitors (or Electric Double-Layer Capacitors – EDLCs) are a relatively new kind of
device which is used for quick harvesting and delivery of electricity. They are implemented for
electricity management and improving energy efficiency of stationary and mobile systems. Hence,
they play a major role for developing cleaner systems.
Most of the current research on supercapacitors is oriented to energy density enhancement, in
order to broaden their application spectrum. As given by formula E = ½CU2, energy is highly
depending on voltage U, the latter being controlled by the stability window of the electrolyte.
Therefore, most of the commercially available systems use organic electrolyte, e.g., NEt4BF4 in
acetonitrile, allowing 2.7–2.8 V to be reached. Due to the relatively high cost of these devices and
environmental unfriendly character of these electrolytes, alternative solutions such as use of protic
electrolytes must be investigated.
Until recently, H2SO4 and KOH were mainly considered as aqueous electrolytes for
supercapacitors, giving voltages of 0.7–0.8 V. By the use of neutral alkali sulfate solutions, we have
demonstrated voltages up to ca. 2 V for AC/AC capacitors1,2
. Such high values are possible owing to
the high over-potential for di-hydrogen evolution related to the pH increase in the porosity of the
carbon negative electrode3. This presentation will show the various steps in the development of a
prototype, utilizing safe, cost effective and environmental friendly materials.
Acknowledgements: The Foundation for Polish Science is acknowledged for supporting the
ECOLCAP project realized within the WELCOME program, co-financed from European Union
Regional Development Fund.
1 L. Demarconnay, E. Raymundo-Piñero, F. Béguin “A symmetric carbon/carbon supercapacitor operating at 1.6 V by using
a neutral aqueous electrolyte”, Electrochem. Commun. 12, 2010, 1275-1278.
2 K. Fic, G. Lota, M. Meller, E. Frackowiak “Novel insight into neutral medium as electrolyte for high-voltage
supercapacitors”, Energy Environ. Sci. 5, 2012, 5842-5850.
3 . ao, L. Demarconnay, E. Raymundo-Piñero, F. Béguin “Exploring the large voltage range of carbon/carbon
supercapacitors in aqueous lithium sulfate electrolyte”, Energy Environ. Sci. 5, 2012, 9611-9617.
15
Motion of a spherical particle near a planar fluid-fluid interface:
The effect of surface incompressibility
Jerzy Blawzdziewicz1, Maria L. Ekiel-Jezewska
2, Eligiusz Wajnryb
2
1Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409-1021, USA
2Institute of Fundamental Technological Research, Polish Academy of Sciences,
Pawinskiego 5B, 02-106 Warsaw, Poland
Email of the presenting author: [email protected]
Hydrodynamic coupling of a spherical particle to an undeformable planar fluid-fluid interface
under creeping-flow conditions is discussed 1-2
. The interface can be either surfactant-free or covered
with an incompressible surfactant monolayer. In the incompressible surfactant limit, a uniform
surfactant concentration is maintained by Marangoni stresses associated with infinitesimal surfactant
redistribution. Our detailed numerical calculations show that the effect of surface incompressibility
on lateral particle motion is accurately accounted for by the first reflection of the flow from the
interface. For small particle-interface distances, the remaining contributions are significant, but they
are weakly affected by the surface incompressibility. We show that for small particle-wall gaps, the
transverse and lateral particle resistance coefficients can be rescaled onto corresponding universal
master curves. The scaling functions depend on a scaling variable that combines the particle-wall gap
with the viscosity ratio between fluids on both sides of the interface. A logarithmic dependence of the
contact value of the lateral resistance function on the viscosity ratio is derived. Accurate numerical
calculations are performed using our Cartesian representation method.
1 J. Blawzdziewicz, M. L. Ekiel-Jezewska, and E. Wajnryb (2010): Motion of a spherical particle near a planar fluid-fluid
interface: The effect of surface incompressibility, J. Chem. Phys. 133, 114702-1--12.
2 J. Blawzdziewicz, M. L. Ekiel-Jezewska, and E. Wajnryb (2010): Hydrodynamic coupling of spherical particles to a
planar fluid-fluid interface: Theoretical analysis, J. Chem. Phys. 133, 114703-1--11.
16
Environmental and medical technologies:
Link between science and industry
Jacek Bodasiński1, Leon radoń
2
1 Secura Nova Ltd. & Microspun R&D Team., Warsaw, Poland, [email protected]
2 Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw, [email protected]
Secura Nova Ltd. and its Microspun R&D Team is focused on selected environmental and
medical technologies which are developed in cooperation with the Faculty of Chemical and Process
Engineering at Warsaw University of Technology (FCPE WUT). Depth filtration is used for removing
solid or liquid phase particles from liquids and gases by filtering suspended matter against a layer
composed of grains or fibers. Fruitful cooperation between the Company and FCPE WUT results in
generation of innovative technological solutions, which provide the implementation of new filtration
processes and new products 1. Recent R&D program includes:
- increasing the efficiency and lifetime of absolute filters,
- aerosol filtration,
- developing of the production of nanofibers from different polymers,
- designing filtration materials and cartridges with the nanofibers
- developing technology of producing nanofibers with implemented electrical charge (electret
fibers).
- designing coalescers for different applications
- enhancing performance of pleated filter cartridges
The research and production capability of Secura Nova together with the research potential of
the Faculty (staff, laboratories, production, etc.) led to the cooperation which brought many custom
and unique solutions that were implemented in production2. Recently, new filter structures combining
nano- and microfibers have been developed. Filter media produced by this method may be used to
efficiently remove nano- and submicron particles from liquids and gases.
Another filed of the activity of the Company is focused on optimization of medical devices
intended for drug delivery by inhalation of aerosols produced by liquid atomization3. The research is
also done in cooperation with the FCPE WUT and allows to establish national guidelines in
nebulization technology 4.
1 Bodasiński J., radoń L et al. (2007). Method and apparatus for making filter element, including multi-characteristic filter
element - PCT Patent 2007/143243.
2 http://www.microspun.com.pl
3 http://www.securanova.com.pl
4 Pirożyński M., Ed. (2012). Practical aspects of nebulization, Alfa Medica Press, Bielsko Biała, Poland – book in Polish
17
Description of the bubble shape on an inclined plane
Zuzana Brabcová, Pavlína Basařová, Michal Seifert
Department of Chemical Engineering, Institute of Chemical Technology Prague, Prague, Czech Rep.,
The bubble-particle interaction is an important process playing the key role in numerous
industrial applications, e.g. in flotation or multiphase reactors. The succesful interaction between the
bubble and the solid particle is influenced by the approaching of the bubble to a collision distance, in
which the bubble-particle contact occurs. The liquid film between the bubble and the particle surface
is then formed and due to the affection of intermolecular and interfacial forces it thins to the rupture.
The three-phase contact (TPC) is established and expands to the equilibrium state, when the TPC
diameter does not change – a stable aggregate of the bubble and the particle is formed. All
mathematical models which describe the TPC line expansion utilize the knowledge of dynamic and
equilibrium contact angles. The description of a drop or a bubble placed on an inclined plane or
curved surface is very complicated. Up to now few methods were published, but these methods are
not suitable for the description of sizeable amount of data. The adhering bubble is not symmetric (as
in the case of a horizontal plane); therefore contact angles on the right and left side of the bubble
differ. The aim of this project is to find out the methodology for relatively simple and fast calculations
of contact angles. The special attention was paid on the ability of the model to describe the bubble
shape during the adhesion on hydrophobic solid surface.When compared with the liquid drop placed
on an inclined plane, the bubble holds nearly a spherical shape and contact angles in the upper and
lower bubble end differ only little. The basic idea of our method is to divide the bubble into two parts
and describe these parts separately. A set of points around the bubble is obtained and then the ADSA
methodology is used. This method utilizes the Laplace equation of the capillarity; the bubble profile
and the contact angle are evaluated using the set of experimental points around the edge of the bubble.
The comparison of the experimental and calculated bubble profile shows a good agreement, the error
in contact angle calculation is comparable with accuracy of the experimental measurement. The
process of the adhesion was recorded using high-speed digital camera and images were evaluated
using the image analysis software NIS-Elements. Calculations were performed using the MatLab
software.
18
Droplets of pure and complex fluids evaporation:
wetting, instabilities and pattern formation
Florian Carle, Wassim Bouzeid, David Brutin
IUSTI Laboratory, UMR 7343 CNRS, Aix Marseille University, Marseille, France, [email protected]
We investigate several aspects of sessile drop evaporation. Pure and complex fluids are studied
and cover a wide range of applications. Complex fluids include nanofluids and biological fluids such
as human blood1. Different tools are used to quantitatively measure the evaporation rate but also to
analyze flow instabilities. Experiments performed under microgravity conditions aims to bring new
insight thanks to a reduced gravity influence on the evaporation2. Thermo-capillary phenomena can
develop but also the wetting and spreading is modified. The influence of the triple line dynamics on
the evaporation using pure fluids3 has been demonstrated including the thermal aspects. Now we are
looking at the same triple line dynamics with complex fluids also including the heat transfer
mechanisms.
Dry-out of different droplets natures [Top left (24 nm polystyrene nanoparticles), Top right
(polymer by L. Pauchard) – Bottom left (human blood) – Bottom right (colloids by D. Fairhurst)]
1 Brutin D., Sobac B., Loquet B., Sampol J. (2011): Pattern formation in drying drops of blood, J. Fluid Mech., 667, 85-95.
2 F; Carle, B. Sobac, D. Brutin (2012): Hydrothermal waves on ethanol droplets evaporating under terrestrial and reduced
gravity levels, J. Fluid Mech., 712, 614-623.
3 Sobac B., Brutin D. (2011): Triple-line behavior and wettability controlled by nano-coated substrates: Influence on sessile
drop evaporation, Langmuir, 27, 14999-15007.
19
Multiphase Fluids in Confined Flow
Sergio Caserta1, Antonio Perazzo
2, Valentina Preziosi
3, Rosa D’Apolito
4, Giovanna
Tomaiuolo5, Angelo Pommella
6, Stefano Guido
7
Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale,
University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy. [email protected], [email protected], [email protected], [email protected],
[email protected],[email protected], [email protected]
Microfluidics is the science and technology that process or manipulate small amount of fluids.
In this work we show how microfluidic can be useful to quantify droplet deformability and emulsion
interfacial properties. Confined droplets flow and deformation in microchannels is a topic of
considerable importance because of its industrial implications. To get some insight of a wide range of
processes, such as multiphase flow in porous media, process intensification of multiphase fluids, etc.,
a full comprehension of these phenomena is needed. In our experimental setup a circular cross section
glass capillary is placed under the field of view of an optical microscope and the droplet deformation
in confined flow is determined by image analysis techniques. Newtonian model system was used to
investigate the morphology in transient and steady state flow of droplets having undeformed radius
comparable to the capillary size. Drop deformation and velocity as a function of the Capillary number,
and of the confinement have been investigated. Stream line inside and outside the drops have also
been experimentally determined. Good agreement with theoretical models and numerical simulations
available in the literature has been found. A measurement of the transient in the drop deformation, due
to extensional flow under convergent-divergent geometry is used to calculate interfacial tension.
Squires, T. M., Quake, S. R. (2005): Microfluidics: fluid physics at the nanoliter scale, Rev Mod Phys, 77, 977-1026.
De Mello, A. J. (2006) Control and detection of chemical reaction in microfluidic systems, Nature, 442, 394-402.
Whitesides G.M. (2006) The origins and the future of microfluidics, Nature, 442, 368-373.
Guido, S., Preziosi, V. (2010) Droplet deformation under confined Poiseuille flow, Adv Coll Int Sci, 161, 89-101.
Xia, Y., Whitesides, G. M. (1998) Soft litography, Angewandte Chemie Int Ed, 37, 550-575.
Tomaiuolo, G., Barra, M., Preziosi, V., Cassinese, A., Rotoli B., Guido, S. (2011): Microfluidics analysis of red blood cell
membrane viscoelasticity, Lab Chip, 11, 449-454
20
Coalescence of particles with solid core and viscous shell
Ram Dayal1, Eberhard Abele
2,3 and
Tatiana Gambaryan-Roisman
1,3
1 Technische Universität Darmstadt, ,Institute of Technical Thermodynamics, Petersenstr. 17, Darmstadt, 64287,
Germany 2Technische Universität Darmstadt, Institute of Production Management, Technology and Machine Tools,
Petersenstr. 30, Darmstadt, 64287, Germany 3Technische Universität Darmstadt, Center of Smart Interfaces, Petersenstr. 17, Darmstadt, 64287, Germany
Coalescence of particles with solid cores and viscous shell plays an important role in chemical
and pharmaceutical industry, in agriculture and in production technology. Coalescence of metal
particles, which are partially melted due the laser heating, is an important mechanism responsible for
densification of metal powder during selective laser sintering process.
Our model describes coalescence of two or more particles consisting of a solid core and a liquid
shell. The flow in the liquid shell is driven by the surface tension. It is assumed that the characteristic
Reynolds number is low, so that the creeping flow model can be applied. A two dimensional
boundary element model (BEM) is used to solve the governing equations. The numerical model is
validated by comparison with available analytical solution for the limiting case of fully viscous
particles.
The influence of the liquid properties, the sizes of the particles and the relative sizes of the solid
core on the two-phase flow and on the shape evolution of coalescing particles is quantified. In
application to the selective laser sintering process densification rate has been defined as an important
output parameter. We show that increasing of the solid core radius leads to the decrease of the powder
densification rate.
21
Nanostructure-assisted hydrogen generation by hydro-/thermo-lysis of
boranes
Umit B. Demirci
IEM (Institut Europeen des Membranes), UMR 5635 (CNRS-ENSCM-UM2), Universite Montpellier 2, Place E. Bataillon,
F- 34095, Montpellier, France, [email protected]
Of the wheels of the hydrogen economy, the storage is certainly “the biggest roadblock to the
widespread use of hydrogen”.1 Several technologies are investigated but chemical hydrogen storage is
particularly attractive owing to high gravimetric hydrogen densities. Typical examples are the boron-
based materials, represented by sodium borohydride NaBH4 and ammonia borane NH3BH3.2
Hydrolytic dehydrogenation of NaBH4 (Eq. 1), NH3NH3 (Eq. 2) or hydrazine borane N2H4BH3
(Eq. 3) has attracted a great attention:
NaBH4 + 4 H2O → NaB(OH)4 + 4 H2 (1)
NH3BH3 + 3 H2O → NH3 + B(OH)3 + 3 H2 (2)
N2H4BH3 + 3 H2O → N2 + B(OH)3 + 5 H2 (3)
The most investigated aspect has been the metal-based
catalysts from which It is expected conversion of 100%,
selectivity in H2 of 100% and durability over cycles. An
example of nanostructured cobalt catalyst we have
developed is shown in Fig. 1.3 This example as well as
others will be presented and discussed during the joint
meeting COST.
Thermolytic dehydrogenation of NH3BH3 is a complex reaction through which 2 equiv. H2 are
released at <200 °C (Eq. 4):
NH3BH3 → [NH2BH2] + H2 → [NHBH] + 2 H2 (4)
To improve the dehydrogenation properties – the objectives
are to decrease the onset of dehydrogenation and avoid the
release of unwanted borazine – several strategies have been
tested, and one focuses on the hydride nanoconfinement into
porous hosts. In this context, we have developed boron
nitride hollow spheres (Fig. 2). When NH3BH3 is confined
within the core of these particles, it dehydrogenates from 50
°C and the generated H2 is pure.4 This example will be
presented and discussed during the joint meeting COST.
To sum up, nanostructured materials are important in the field of boron-based hydrogen storage
materials and our last results will be presented during the joint meeting COST MP1103.
1 Ritter J.A., Ebner A.D., Wang J., Zidan R. (2003): Implementing a hydrogen economy. Mater Today 6, 18−23.
2 Moussa G., Moury R., Demirci U.B., Sener T., Miele P. (2013): Boron-based hydrides for chemical hydrogen storage. Int J
Energy Res in press.
3 Bechelany M., Abou-Chaaya A., Frances F., Akdim O., Cot D., Demirci U.B., Miele P. (2013): Nanowires with controlled
porosity for hydrogen production. J Mater Chem A 1, 2133-2138.
4 Moussa G., Bernard S., Demirci U.B., Malo S., Miele P. (2013) : Hollow core@mesoporous shell boron nitride
nanopolyhedrons as nanoscaffolds to promote the dehydrogenation of ammoniaborane. Chem Commun submitted.
Fig. 1. Cobalt nanowires.3
Fig. 2. Boron nitride hollow
nanopolyhedrons.4
22
EURAXESS Initiative and EURAXESS Jobs Portal
Sanopoulos Dimitrios1
1 Horizontal Projects Unit - Research Policies and Researchers Activity, Centre for Research and Technology Hellas,
Thessaloniki, Greece, [email protected]
EURAXESS is a European Commission initiative with main goal to strengthen the
attractiveness of European countries towards mobile researchers by removing the barriers to free
movement of knowledge within Europe, by strengthening cross-border mobility of researchers,
students, scientists and academic staff and by providing researchers with better career structures.
EURAXESS is a network consisting in more than 200 Services Centres located in 38 European
countries where you can receive customised assistance on all matters concerning your professional
and daily life according to its services commitment. All services of the EURAXESS Network are free
of charge. In addition each country has developed a national website to provide useful information for
the relocation abroad. For more information, please visit EURAXESS website (www.euraxess.eu)
The EURAXESS Jobs (http://ec.europa.eu/euraxess/jobs) portal is the pan-European market
place for research jobs. It hosts job vacancy adverts from thousands of organisations and through an
agreed cooperation also shows the job vacancies published on NatureJobs, EuroScienceJobs, Galaxy
and other European platforms for research jobs. Furthermore, the researchers may post their CV on
the portal and show their availability for career development in the European Research Area.
EURAXESS Rights (http://ec.europa.eu/euraxess/rights) aims at better employment and
working conditions for researchers throughout Europe, thereby helping to enhance the attractiveness
of European research careers. One of the cornerstones of EURAXESS Rights is the implementation of
the European Charter for Researchers and the Code of Conduct for the Recruitment of Researchers.
The 'Charter & Code' adopted by the European Commission as a Recommendation to the Member
States and address researchers as well as employers and funders in both the public and private sectors.
The Charter provides a framework for the career management of researchers, while the Code
promotes open and transparent recruitment and appraisal procedures. Together they are aimed at
developing an attractive, open and sustainable European labour market for researchers. To facilitate
the implementation of the Charter & Code, guidance is provided by the "Human Resources Strategy
for Researchers incorporating the Charter & Code". This mechanism is put into action on a voluntary
basis, and is as simple as possible, avoiding cumbersome procedures and respecting the variety of
situations across institutions.
In conclusion, EURAXESS is the most reliable and effective official tool of European
Commission for development and further improvement of researchers career in Europe.
23
Generation of foams in Vancomycin HCl by exposure to laser radiation
Andra-Cristina Dinache, Viorel Nastasa, Mihail-Lucian Pascu
Laser Department, National Institute for Laser, Plasma & Radiation Physics, Romania, [email protected]
Vancomycin was designed in 1950’s and it is a glycopeptides antibiotic active against most
gram-positive organisms, including penicillin-resistant staphylococci1,2
.
UV-Vis absorption spectra of Vancomycin hydrochloride solutions in ultrapure de-ionized
water were recorded. The absorption spectra have a broad peak at 280nm and exhibit below 250nm
more bands which are partially resolved. Stability studies were performed on Vancomycin
hydrochloride 10-4
M solutions in ultrapure de-ionized water comparing the absorption spectra
recorded at different time intervals after preparation. The samples were stable for at least 24 hours
after they were prepared.
The laser – induced fluorescence (LIF) spectra of Vancomycin hydrochloride 2mg/ml
(~1.35x10-3
M) solutions in ultrapure water were recorded in bulk solutions and in droplets.
The Vancomycin solutions were irradiated with the laser radiation emitted by the forth and
second harmonic generation of a Nd:YAG laser (wavelength = 266nm and 532nm). Pulse repetition
rate was 10 pps. The average beam energy varied between 1mJ and 20mJ, function of the
experimental objectives. The exposure time of each sample also varied. Access of the laser beam to
the sample was made via a shutter, computer controlled or manually, so that the LIF emitted by the
sample was collected after a known number of laser pulses by the same PC via an Ocean Optics
HR4000CG-UV-NIR high-resolution spectrometer. LIF was collected and transmitted to the
spectrometer (spectral resolution: 0.75nm) via an optical fiber (inner core: 1mm)3.
During irradiation foams were obtained. The quantity of foam generated depended on the
experimental conditions (exposure time, energy of the laser beam and volume of the solution).
Spectral modifications of the solutions were observed with UV-Vis absorption spectroscopy
and LIF spectroscopy.
Laser irradiation induces also structural changes, causing generation of foams in Vancomycin
HCl solutions.
1 Levine, D. P. (2006): Vancomycin: A History. Clinical Infectious Diseases 42 (Suppl 1), 5-12
2 Moellering, R.C. Jr. (2006): Vancomycin: A 50-Year Reassessment. Clinical Infectious Diseases 42 (Suppl 1), 3-4
3 Pascu, M. L., Nastasa, V., Smarandache, A., Militaru, A., Martins, A., Viveiros, M., Boni, M., Andrei, I. R., Pascu, A.,
Staicu, A., Molnar, J., Fanning, S., Amaral, L. (2011): Direct Modification of Bioactive Phenothiazines by Exposure to
Laser Radiation. Recent Patents on Anti-Infective Drug Discovery 6, 147-157
24
Decompression Algorithms
Giovanni Distefano1, Georgi Popov
1
1 Mares , S.p.A., Rapallo, Province of Genoa, Italy, [email protected]
Decompression Illness or DCI is the term used for a collection of baurotraumatic symptoms
that can arise after a dive, caused by the change in ambient pressure around the body of a scuba diver
resurfacing. When resurfacing, a diver must ensure that the dissolved nitrogen is appropriately
eliminated through breathing. If the rate of ascent is too fast, the nitrogen precipitates and forms
bubbles in tissues or in the blood stream that grow to a size causing damage1 as they are now too big
to pass from the capillaries to the pulmonary alveoli and be expired out of the body. The risk of DCI
is usually managed in the scuba diving community by adhering to official guidelines dictating the
ascent rate and time to spend at each depth to limit the number and size of bubbles created.
After presenting the basic definitions of scuba diving and different current classifications, the
main problems that can arise from decompression failure will be presented, before discussing the
different models and bubble dynamics used to prevent them. The Haldane-Bülhmann dissolved gas
phase tracking models2 and the Dual Phase models incorporating bubble dynamics
3 will be discussed,
as well as the probabilistic, DCIEM, slab diffusion and exponential-linear models4,5
, focusing on the
unknown physics related to bubble generation and growth in vivo and physiological factors that
influence them6-9
.
1 Beck T.W., Daniels S., Paton W.D.M., Smith E.B. (1978) Detection of bubbles in decompression sickness. Nature.
276:173-4.
2 Workman R.D. (1965); Calculations of decompression schedules for nitrogen-oxygen and helium-oxygen dives. US NEDU
Technical report, Research Report 6:65.
3 Spencer M.P. (1976); Decompression limits for compressed air determined by ultrasonically determined blood bubbles. J
Appl Physiol. 40:227.
4 Weathersby, P.K. et.al. (1984); On the likelihood of decompression sickness. J Appl Physiol. 57:815-825
5 Nishi, R.Y., Lauckner, G.R. (1984); Development of the dciem 1983 decompression model for compressed air diving.
Technical report, DCIEM Report 44-R-44, 1984.
6 Germonpré, P., Pontier, J.-M., Gempp, E., Blatteau, J.-E., Deneweth, S., Lafère, P., Marroni, A., Balestra, C. (2009); Pre-
dive vibration effect on bubble formation after a 30-m dive requiring a decompression stop. Aviat Space Environ Med 80:
12, 1044-1048
7 Gempp, E., Blatteau, J.-E., Pontier, J.-M., Balestra, C., Louge, P. (2008); Preventive Effect Of Pre-Dive Hydration On
Bubble Formation In Divers. Br J Sports Med 43:224-228
8 Toner C.B., Ball R. (2004); The effect of temperature on decompression and decompression sickness risk: A critical
review. US Navy technical report: Naval Medical Research Center (NMRC)
9 Claybaugh J.R., Lin Y.-C. (2004); Exercise and decompression sickness: a matter of intensity and timing. J Phys. 555:588.
25
Drying in porous media
Dario Donnarumma1, Sergio Caserta
2, Giovanna Tomaiuolo
3, Stefano Guido
4
Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale,
University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy. 1 [email protected], 2 [email protected], 3 [email protected],4 [email protected]
Drying processes in porous media lead to the removal of water or other liquid from solid
materials, in order to reduce the content of residual liquid up to a sufficiently low value. These
processes are very common in many industrial manufacturing, typically being the final stage of a
sequence of operations. The drying in a porous medium containing a certain percentage of moisture is
a thermal process; many materials can be dried by heating to a temperature higher than the liquid
boiling point. Typically to remove the moisture from porous solids also involves the transport of the
liquid phase through mechanisms that may be different depending on the microstructure of the
substrata. A generalized analysis of the drying process applicable to every type of material is not yet
available: differences in shape and size of the porous medium, humidity content, matter and heat
transport mechanisms, prevent the development of an universal description, although there are some
general references. The way in which the temperature changes inside the dryer, for example, depends
on the liquid nature and concentration inside the treated product, on the temperature of the heating
medium, on the duration of the process and on the final temperature of the bone dried solid.
26
Novel Materials and Systems for Solid Hydrogen Storage
Martin Dornheim
Helmholtz‐Zentrum Geesthacht, Germany, [email protected]
27
Multi-functional complex liquids for coating semi/porous surfaces
Victoria Dutschk1, Majid Nasiri Boroumand
1, Francesco de Rosa
2, Jie Zhao
1,3
1EFSM Industrial Research Group, University of Twente, the Netherlands, [email protected]
2Politecnico di Torino, Italy
3AkzoNobel, The Netherlands
Intensive development of nanotechnology linked with generation of nanostructures and
nanomaterials offers great possibilities of creating modern multifunctional materials. Such materials
based on semi-porous surfaces, e.g. textile substrates, can have very wide applications due to the new
properties and functions rendered to these substrates such as self-cleaning, anti-bacterial, UV
protection, flame resistance, super hydrophobicity, electrical conductivity, friction and wear
resistance, environmental purification, pH/thermo-responsive hydrophobicity or hydrophilicity1,2
. The
ultimate impact of nanotechnology in the area of textile and other potential application areas will
depend on the type and structure of nano-structured functional agents and their coating process3.
Among established wet-chemical modifications processes, inkjet printing techniques can be
used as a novel approach with high efficiency and low cost to deposit functional agents on fabric
surfaces. In our studies, a multi-functional formulations, containing various functional agents which
have high affinity to natural and/or synthetic smooth (foils) and semi-porous (textile materials) will be
prepared. Semi/porous materials such as polymeric fabrics will be multi-functionalized by the
multifunctional formulations including nanoparticles (NPs) with specific properties using wet-
chemical and inkjet printing process. The discussed nano-structured functional agents include oxide
nanoparticles such as TiO2, ZnO, Ag as well as artificial and natural nano-clays.
The future studies will be dedicated to semiconductor nanomaterials.
1 Qi, K., Daoud, W.A., Xin, J.H., Mak, C.L., Tang, W., Cheung, W.P. (2006): Self-cleaning cotton. Journal of Materials
Chemistry 16, 4561-4566. 2 Dastjerdi, R., Montazer, M. (2010): A review on the application of inorganic nano-structured materials in the modification
of textiles: Focus on anti-microbial properties. Colloids and Surfaces B: Biointerfaces 79, 5-18. 3 Baer, D.R., Burrows, P.E., El-Azab, A.A. (2003): Enhancing coating functionality using nanoscience and nanotechnology.
Progress in Organic Coatings 47, 342-356.
28
Dynamic adsorption of dissolved oil compounds in produced water onto
air bubbles: Influence of crude oil and water composition
Mona Eftekhardadkhah, Gisle Øye
Ugelstad Laboratory, Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU),
Trondheim, Norway, [email protected]
This study aims at understanding how the surface properties of air bubbles are influenced by
adsorption of dissolved hydrocarbons present in produced water. The general aim is to obtain better
understanding of mechanisms affecting the oil removal efficiency during flotation processes.
Particular focus has been put on determining the influence of crude oil and water composition, both
on the characteristics of produced water and on the surface properties of air bubbles. The dynamic
surface tension of simulated produced water samples was measured by maximum bubble pressure
tensiometry, and the adsorption mechanism of the dissolved hydrocarbons onto air bubbles was
predicted based on diffusion controlled adsorption kinetics1, 2
. The adsorption process deviates from
the diffusion-controlled mechanism for a long-time adsorption process. The concentration of
dissolved hydrocarbons was smaller in the presence of salts (salting-out effect) 3 and an adsorption
barrier appears at short surface ages. The influence of divalent ions (Ca2+
, Mg2+
) was not very
significant. Moreover, the water soluble acidic and basic crude oil compounds exhibit various degrees
of surface activity and different adsorption kinetics onto air/water interface was observed for the
produced water samples prepared with different crude oils.
1 Liu, J., C. Wang, U. Messow (2004): Adsorption kinetics at air/solution interface studied by maximum bubble pressure
method. Colloid & Polymer Science 283, 139-144.
2 Nguyen, A.V., C.M. Phan, G.M. Evans (2006): Effect of the bubble size on the dynamic adsorption of frothers and
collectors in flotation. International Journal of Mineral Processing 79, 18-26.
3 Stanford, L.A., Kim, S., Klein, G. C., Smith, D. F., Rodgers, R. P., Marshall, A. G. (2007): Identification of Water-Soluble
Heavy Crude Oil Organic-Acids, Bases, and Neutrals by Electrospray Ionization and Field Desorption Ionization Fourier
Transform Ion Cyclotron Resonance Mass Spectrometry. Environmental Science & Technology 41, 2696-2702.
29
Electrodeposition of Ni-Cu and Ni-Co-Cu porous foams using hydrogen
bubble template
Sónia Eugénio1, Maria João Carmezim
1,3, Maria Teresa Silva
1,4, Fátima Montemor
1,2
1 ICEMS-Instituto Superior Técnico, Technical niversity of Lisbon, Lisbon, Portugal s.eugenio ist.utl.pt
2 Department of Chemical Engineering, nstituto Superior Técnico, Technical niversity of Lisbon, Lisbon, Portugal
[email protected] 3Department of Mechanical Engineering, ESTSet bal, nstituto Politécnico de Set bal, Set bal, Portugal
[email protected] 4Department of Mechanical Engineering, Instituto Superior de Engenharia de Lisboa, Lisbon, Portugal;
Electrodeposition is a widespread technique for the production of both decorative and
functional coatings. During cathodic deposition of most metals from aqueous media, hydrogen
evolution is inevitable and commonly viewed as detrimental, reducing the current efficiency of the
deposition process and inducing unwanted porosity in dense coatings. On the other hand it is possible
to take advantage of hydrogen bubble formation during electrodeposition and use it as a dynamic
template for the production of porous 3-dimensional foam-like architectures (Figure 1). This process
was described by Shin et al.1, 2
for the electrodeposition of 3-dimensional porous copper foams, about
100 m thick, with nanostructured pore walls. Such structures provide a high specific area which is
one of the most important characteristics of electrodes for supercapacitors, in order to promote fast
electrochemical reactions and charge transfer.
In the present work, Ni-Cu and Ni-Co-Cu foams were produced by electrodeposition using an
in-situ dynamic hydrogen bubble template. SEM analysis revealed that they have a nanostructured
morphology consisting of micrometric pores with dendritic wall (Figure 2). The morphology and
chemical composition of the foams was related to the deposition parameters, namely electrolyte
composition, applied current and deposition time. Furthermore, their electrochemical behavior and
specific capacitance were studied by cyclic voltammetry and chronopotentiometry in order to assess
their application as electrodes for supercapacitors.
Figure 1.Schematic representation of metal foam formed by electrodeposition using a hydrogen
bubble template.
Figure 2. Microstructure of electrodeposited Ni-Cu metal foams.
1 Shin, H.-C., Dong, J., Liu, M. (2003) Nanoporous structures prepared by an electrochemical deposition process Adv Mater
15, 1610-1614
2 Shin, H.-C., Liu, M. (2004): Copper foam structures with highly porous nanostructured walls Chem Mater 16, 5460-5464.
30
An electrical technique for detection of micro-bubbles in living subjects
with in-vitro validation
Sotiris P. Evgenidis1, Konstantinos Zacharias
1, Thodoris D. Karapantsios
1, Ioannis Savvas
2, Kiriaki
Pavlidou2, Lysimachos Papazoglou
2, Michail Patsikas
2
1 Division of Chemical Technology, School of Chemistry, Aristotle University, University Box 116,
GR-54124, Thessaloniki, Greece, [email protected] 2 Faculty of Veterinary Medicine, Aristotle University, Voutyra Street 11, GR-54627, Thessaloniki, Greece
The objective of the present study is the detection and characterization of micro-bubbles in
human bloodstream due to Decompression Sickness (DCS), using an innovative technique that
measures with great sensitivity the electrical conductance of human tissues. The focus is on being
non-intrusive but yet capable of detecting features far away from vein walls and on attaining high
sensitivity even for low gas volumetric concentrations as those encountered during DCS. Work so far
includes in-vivo testing of the technique on anesthetized swines and in-vitro validation by making
experiments in tubes and mimicking tissues. In both cases, the technique analyzes and processes the
electrical footprints of gas volumetric concentration variations in order to provide information about
bubbles characteristics in bubbly flows. In-vitro testing concluded having achieved superb
measurement sensitivity (~0.00001) that can reliably sense bubble sizes from ~10 μm to ~700 μm for
gas volumetric concentrations between ~0.001 and ~0.1. This holds for both static and flow (steady
and pulsatile) conditions concerning liquids of variable salinity and viscosity and for liquid velocities
from 3 to 30 cm/s. In-vivo tests conducted on anesthetized swines demonstrated that electrical
technique’s measurement sensitivity is adequate to sense the presence of bubbles ~20 μm in blood
flow by placing electrodes over partially conductive tissues & skin and documented
ultrasonographically. Additionally, the application of advanced post-processing methods on data
collected from both in-vitro and in-vivo tests showed that spectral analysis (such as wavelet,
spectrogram and FFT analysis) enhances considerably bubbles detection and characterization.
Concluding, the results of the work so far are considered promising for the forthcoming tests on
humans, making an effort to sense micro-bubbles generated during DCS in blood flow.
31
Wide tuning of interfacial viscoelasticity and bulk rheology using
thermoresponsive supramolecular assemblies of fatty acids
Anne-Laure Fameau1, Arnaud Saint-Jalmes
2
1 BIA, Institut National de la Recherche Agronomique, Nantes, France [email protected]
2 IPR, Institut de Physique de Rennes, Rennes, France, [email protected]
Over the last years, the research group at BIA-INRA has designed and studied a simple and
sustainable system consisting in a 12 hydroxy stearic acid (12-HSA) in association with an
organic counter-ion (such as ethanolamine or hexanolamine): this combination allows us to
successfully disperse the - a priori highly insoluble - monomers of 12-HSA in water, and to get self-
assembled tubes of around 10 µm length and 600 nm diameter. Interestingly, this supramolecular
morphology is also temperature-dependent: the tube structural parameters vary with T, and the system
also exhibit a clear and reversible “tube-micelle” transition.
As a result of a collaboration between the BIA and IPR groups, we report here results on how
this thermo-responsivity of the supramolecular morphology has an impact on both interfacial
viscoelasticity and bulk dynamical properties. At all scales and as a function of the temperature, we
have been able to draw direct correlation between the supramolecular self-organization and the
macroscopic properties. In particular, we show that a fine and non-monotonous control of the
rheological properties can be found by changing the temperature while remaining within the “tube
phase”, and that drastic variations on interfaces and bulk are obtained as the “tube-micelle” transition
is crossed.
32
Proteins/nanoparticles interactions in the toxicity of nanomaterials
Ivana Fenoglio, Arianna Marucco, Francesco Turci, Elena Ghibaudi
Department of Chemistry, “ . Scansetti” nterdepartmental Center for Studies on Asbestos and other Toxic Particulates and
Interdepartmental Center for Nanostructured Interfaces and Surfaces, University of Torino, Italy.
The rapid development of nanotechnologies has raised some concerns on the potential effects
on human health and on the environment of engineered nanoparticles. At the same time nanoparticles
attract intense interest for their potential applications in diagnostic and therapy. The ability to cross
biological barriers or the occurrence of specific chemical reactivity makes them very different entities
from their micrometric counterparts. Therefore, the behavior of nanoparticles in living organisms is
difficult to be predicted.
The fate of particles inside living organisms and their possible adverse effects strongly depend
on the early events occurring when they reach the biological fluids. Among these events the
interaction of nanoparticles with proteins appears to be a crucial issue.1,2,3
The irreversible adsorption of biomolecules to a surface may lead to modification of the
biofluid composition. At the same time, surface-driven conformational changes of macromolecules or
a selectively oriented adsorption may enhance or inhibit the activity of enzymes or influence the
molecular recognition of biomolecules. Oxidative reactions promoted by the surface may impair the
biomolecules. Finally, the formation of a stable layer of biomolecules at the interface may modify the
surface properties of the materials or the aggregation state in the case of nanoparticles3.
There are several indications that the occurrence of adverse reactions to a biomaterial depends
upon the nature of the surface4. However, the comprehension of the processes occurring at the
surface/biofluid interface at a molecular level as well as the identification of the determinants driving
such processes is still at the early stages.
A big effort has been made in the last years within the
scientific community and regulatory agencies to set up protocols
suitable for predicting the possible toxicity of nanoparticles. In
this perspective, the investigation of the mechanisms of
interaction between nanoparticles and proteins is of great
importance.
An overview on the experimental approaches to study the
chemical and physical interactions between inorganic surfaces
and proteins will be here discussed.
1 Nel A.E., Madler L., Velegol D., Xia T., Hoek E.M.V., Somasundaran P., Klaessig F., Castranova V., Thompson M.,
(2009): Understanding biophysicochemical interactions at the nano-bio interface, Nature Materials 8, 543–557
2 Walczyk D., Bombelli F.B., Monopoli M.P., Lynch I., Dawson K.A. (2010): What the cell “sees” in bionanoscience, J. Am.
Chem. Soc. 132 5761–5768.
3Fenoglio I., Fubini B., Ghibaudi E., Turci. (2012): Adv. Drug Deliv. Rev. 63, 1186-1209.
4 Norde W., My voyage of discovery to proteins in flatland…and beyond, (2008): Colloids and Surfaces. B, Biointerfaces 61
1–9.
33
Smart Materials for Additive Manufacturing
James K. Ferri1*
, Robert Wood2 and Howard A. Kuhn
2
1 Department of Chemical and Biomolecular Engineering, Lafayette College, Easton, Pennsylvania, USA
2 The ExOne Company, Pittsburgh, Pennsylvania, USA
Additive manufacturing is a relatively new and expanding manufacturing strategy that can be
used to design sophisticated structures from a host of materials, including metals, ceramics, and
polymers with lower cost and less generated waste. Three-dimensional printing provides advantages
to traditional molding and metal casting with regards to speed, cost, and ease of production enabling
rapid feedback in prototype design and disruptive manufacturing pricing models. Additionally,
threedimensional printing enables highly detailed internal and external geometries, creating new paths
to complex part manufacturing.
The ExOne ProMetal process utilizes a layer-by-layer technique in which alternating layers of
powder and a binding agent are serially assembled. The binder serves to provide intralayer (x,y)
binding as well as (z) stitching. The binder is delivered though a piezoelectric printhead and actuated
via robotic control. Manufacture involves essentially three phases: 1) printing, 2) curing, and 3)
sintering to produce a finished part. We discuss current strategies to optimize the manufacturing
process via the use of smart binder systems to decrease defect frequency and increase overall
fabrication rate.
34
Programmable Thermoresponsive Polymers for Interfacial Stabilization
Filippo Gambinossi1, Munish Chanana
2, Steven E. Mylon
3, James K. Ferri
1*
1 Department of Chemical and Biomolecular Engineering, Lafayette College, Easton, Pennsylvania, USA
2 ETH Zurich, Zurich, Switzerland 3 Department of Chemistry, Lafayette College, Easton, Pennsylvania, USA
Stimulus-responsive nanoparticles can be used to exert control on the stability of disperse
fluid/fluid systems, however the mechanisms by which this occurs are only partially understood. This
is, in part, due to the competition between the dynamic mechanisms interfacial relaxation processes
and colloidal aggregation rates – both of which are largely unexplored. Here, we discuss a new class
of thermosensitive polymeric materials based on random copolymers of di(ethylene glycol) methyl
ether methacrylate (MeO2MA) and poly(ethylene glycol) methyl ether methacrylate (OEGMA) to
investigate the role of hydrophobicity and physicochemical behavior in suspension on the colloidal
stability. Gold nanoparticles functionalized with thermosensitive polymer brushes of these
copolymers display lower critical solution phenomena (LCST) and switchable aggregation kinetics
(k11) that is strongly dependent on the co-polymer ratio, temperature, and ionic strength. Effects of
these parameters on the aggregation kinetics were studied by time resolved dynamic light scattering
(TR-DLS) experiments. We observe a linear superposition between the critical NaCl coagulation
concentration (CCC), temperature, and co-polymer composition resulting in a programmable
aggregation that can be exploited for design of thermoresponsive foam and emulsion stability. We
also discuss potential applications of these materials for self-cleaning interfaces via thermoresponsive
adhesion modulation and interrogating the immunobiology of engineered nanomaterials.
1 Edwards, E. W.; Chanana, M.; Wang, D.; Moehwald, H. Angewandte Chemie-International Edition 2008, 47, 320-323.
35
Acoustic manipulation of rising bubbles at different gravity levels
Anna Garcia-Sabaté1, Roger Farrarons
1, Ricard González-Cinca
1
1 Applied Physics Department, Universitat Politècnica de Catalunya-BarcelonaTech, Castelldefels, Spain,
Bubbles rising in fluids can easily be found in a wide variety of situations, from simple daily
objects (e.g. bubbles in a glass of sparkling water) to more sophisticated devices (e.g. bubble column
reactors). Many of these systems require a certain level of control on bubbles. Acoustic waves have
been proved to be an efficient method to control bubble dynamics1,2
, but still further research is
required, especially under different gravity levels.
We have carried out an experimental study on the effects of acoustic waves on rising air
bubbles at gravity levels ranging from 2g to 19.3g. The experiments were conducted in the frame of
the European Space Agency contest “Spin Your Thesis! 2012”. Bubbles were injected into the test
cell through a 0.15mm (internal diameter) needle by means of a syringe pump. The dynamics of the
injected bubbles was modified by the effects of an acoustic standing wave generated by two
piezoceramic transducers glued to the walls of the cubic cell (one on one side and one on the bottom)
and driven by the amplified signal of a function generator.
The primary Bjerknes force3 is responsible for the movement of the bubbles towards the
pressure nodes. The secondary Bjerknes force3
takes into account the attraction and repulsion between
bubbles. The effects of these forces observed in our experiments are diverse. We have analyzed the
bubble size at detachment from the nozzle, the rise path, the levitation, and the attraction or repulsion
of bubbles.
We present a preliminary analysis of the results obtained at different gravity levels and compare
them with results obtained at 1g. A comparison with results obtained without an acoustic wave is also
presented.
1 Y. Abe, M. Kawaji, and T. Watanabe (2002): Study on the bubble motion control by ultrasonic wave. Experimental
Thermal and Fluid Science, vol. 26, no. 6-7, pp. 817-826.
2 J. M. Fan and Z. Cui (2005): Effect of Acoustic Standing Wave in a Bubble Column. Industrial & Engineering Chemistry
Research, vol. 44, pp. 7010-7018.
3 V. F. K. Bjerknes (1904): Fields of Force. The Columbia University Press.
36
Influence of pseudoplasticity and surface tension on gas volumetric
concentration and bubble characteristics in two-phase co-current
upward flow
Petros K. Gkotsis1, Sotiris P. Evgenidis
1, Thodoris D. Karapantsios
1
1 Division of Chemical Technology, School of Chemistry, Aristotle University, University Box 116,
GR-54124, Thessaloniki, Greece, [email protected]
This work studies the way shear thinning and surface tension affect both gas volumetric
concentration and bubble characteristics in upward bubbly flow. In recent years, there has been an
increasing recognition of the importance of non-Newtonian flow characteristics displayed by most
materials encountered in everyday life, both in nature (gums, proteins etc.) and in technology
(polymers and plastics, emulsions, slurries etc.). Blood is a complex multiphase system which in
general exhibits non-Newtonian behavior as well. In this study, the influence of Xanthan gum and
Triton X-100 in a water/glycerol solution is examined in terms of bubbly flow characteristics.
Xanthan gum addition makes the solution pseudoplastic, while Triton X-100 is a surfactant that
lowers surface tension of solution when added. The experiments were conducted in a fully automatic
flow loop, furnished with basic hydraulic devices, measuring sensors and pressure controllers, capable
of generating steady flow conditions of various liquid/gas flow rates. Gas volumetric concentration
measurements were conducted using a novel non-intrusive electrical resistance technique capable of
detecting micro-bubbles with high accuracy and sensitivity, while bubble characteristics were studied
by means of a high resolution camera equipped with proper macro lenses. Data analysis and
processing clearly demonstrate the influence of all parameters examined (Xanthan gum and Triton X-
100 concentration, gas and liquid flow rate) on gas volumetric concentration and bubble
characteristics. It is interesting to notice the presence of voluminous bubble clumps in highly
pseudoplastic fluids which, not only generate a strong attenuation of the electric signal, but also cause
intense fluctuations that seem to follow a periodic pattern.
37
Surface dilatational rheology of triterpenoid and steroid saponins on the
air/water interface
Konstantin Golemanov1, Nevena B. Borisova
2, Slavka Tcholakova
2, Nikolai Denkov
2,
Edward Pelan1, Simeon D. Stoyanov
2,3.4
1 Unilever, Research and Development, Vlaardingen, The Netherlands 2 Department of Chemical Engineering, University of Sofia, Bulgaria
3 Laboratory of Physical Chemistry and Colloid Science, Wageningen University, 6703 HB Wageningen, The Netherlands 4 Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
Saponins are a class of natural surfactants found in more than 500 plant species. They consist
of flat hydrophobic head group (triterpenoid or steroid) with hydrophilic oligosaccharide chains. Due
to their strong surface activity they are good foam stabilizers. To understand and control the
properties of saponin-stabilized foams it is essential to have a detailed knowledge of the surface
rheological properties of these surfactants. In previous articles [1, 2] we studied the rheological
behavior of saponin adsorption layers, subjected to shear deformation. Triterpenoid saponins
exhibited high surface modulus (in shear), G, and complex visco-elastic behavior, while steroids had
very low modulus and viscous behavior. The subject of the current study is the behavior of various
saponins on the air/water interface, subjected to dilatational deformation (steady and oscillatory). We
employed capillary pressure tensiometry (CPT). Different factors were studied: (1) Age of the surface,
tA; (2)Amplitude of deformation, A; (3) Frequency of deformation, . Generally the triterpenoid
saponins had high dilatational modulus, E. The elastic component, E`, was much higher than the
viscous one, E``. E increased with tA and , and decreased with A. The value of E for steroid saponins
was moderate. A comparison was made between the response of the saponins in dilatational and in
shear deformation. We also performed experiments with Langmuir trough (LT). The stress vs.
deformation curves obtained with a LT exhibited hysteresis for triterpenoids, and no hysteresis for
steroids. We compared results obtained with different methods (CPT and LT). Possible correlations
between the structure of the saponins and the respective rheological response are discussed.
1 Golemanov, K.; Tcholakova, S.; Denkov, N. D.; Pelan, E.; Stoyanov, S. D. Surface shear rheology of saponin adsorption
layers. Langmuir 2012, 28, 12071.
2 Golemanov, K.; Tcholakova, S.; Denkov, N. D.; Pelan, E.; Stoyanov, S. D. Comparison of surface shear rheological
properties of triterpenoid and steroid saponins on air-water interface. Langmuir 2013, submitted.
38
Research activities at the UPC-BarcelonaTech Microgravity Laboratory
Ricard González-Cinca, Francesc Suñol, Santiago Arias, Anna Garcia-Sabaté
Applied Physics Department, Universitat Politècnica de Catalunya-BarcelonaTech, Castelldefels (Barcelona), Spain
The Microgravity Laboratory of the Universitat Politècnica de Catalunya-BarcelonaTech
started its research activities at the end of 2005. Numerous experimental, numerical and analytical
studies on multiphase flows have been performed in the laboratory and in different microgravity and
hypergravity platforms since then. The common goal of the majority of these studies consists in the
management of two-phase flows at different gravity levels.
We present an overview of the achievements carried out in the last years as well as some of the
current and future projects in the lab.
39
Hydrogen bonding in zeolite – experiments and possibility to use for
storage
Liga Grinberga, Janis Kleperis, Peteris lesnicenoks, Andris Sivars
Institute of Solid State Physics, University of Latvia; Riga, LV-1063, Latvia; [email protected]
Growing demands of increase of volume for hydrogen storage, for launching hydrogen
industry, leads to new developments in industry and scientific investigation. Due to its structural
variety and almost 3 million theoretical structural combinations to create zeolite structures, it is a
promising material for hydrogen storage. Economical convenience is a good reason to seek simple
and common materials for storage, and natural materials are especially interesting.
Although there are couple of theories about hydrogen’s bonding with zeolite, such as
adsorption, mainly trough Langmuir equations, spillover effect – thanks to strong catalysts which
manipulate hydrogen gas as well as atomic hydrogen, and basic filling of pores, also explained by
Langmuir equations, results are not always consistent. While experimenting and using different
methods to precise the mechanism of adsorption and measuring efficiency some irregularities has
been found. In our work the various experiments using natural zeolite (clinoptilolite) are performed -
mass spectroscopy, Sievert type – volumetric method and thermogravimetry. Effects of low pressure,
air humidity, temperature on adsorption efficiency are investigated to explain their influence on
hydrogen bonding process with zeolite.
40
Rheology of interfacial layers at different density
and degree of entanglement
Theodor D. Gurkov, Rumyana D. Stanimirova, Boryana D. Nenova
Department of Chemical Engineering, University of Sofia, Faculty of Chemistry and Pharmacy,
James Bourchier Avenue 1, Sofia 1164, Bulgaria, [email protected]
This work is focused on the 2D rheological properties of air/ water interfaces covered by
proteins or polymer/ surfactant mixtures. Studies are carried out in a Langmuir trough, where the
layers are deformed by compression/ expansion, and the surface pressure is measured. It is found that
the stress response essentially depends on the extent of association of the molecules, with the
Γaconcomitant restriction on their degree of freedom. The presence of molecules which can be
exchanged reversibly between the interface and the adjacent sub-surface is shown to be related to
Gibbs’ elasticity, EG, and apparent viscosity, ηa . An expression is derived1 to connect ηa with the
kinetic coefficient of mass transfer rate, Kr: ηa = EG/f(Γr)Kr, where f(Γr) depends on the equation of
state due to the reversibly adsorbed molecules, whose amount per unit area is Γr .
On the other hand, some material can be irreversibly attached to the liquid boundary, so that no
exchange with the bulk or the sub-surface is possible. n that case, the respective coverage Γirr is
varied when the layer is shrunk or expanded. Experimentally, one takes the Π(A-1
) isotherm which can
be fitted with an appropriate equation of state see Fig. 1.
Figure 1. Fit of the stress response to
slow compression (10 cm2/min) with
an equation of state for a solute/
solvent binary mixture with an
interaction term 2~ irr (two
adjustable parameters).
We determine the layer
elasticity, E, and discuss its
dependence upon the surface pressure, Π. The rheological response is influenced by the distribution of
molecules among different states of aggregation (mono-, bi- and multi-layers, lumps, etc.). Some time
may be required for the equilibrium distribution to be established. This is usually manifested as
relaxation effects in the rheological properties, connected also with the deformation rate and the
operational prehistory.
1 Gurkov, T. D., Nenova, B., Kostova, E. K., Gaschler, W. (2013): Interfacial rheology of viscoelastic surfactant-polymer
layers. In: Colloid and Interface Chemistry for Nanotechnology, P. Kralchevsky, R. Miller, F. Ravera (Eds.), Chapter 15
(in press). CRC Press Taylor & Francis, Boca Raton, FL, USA.
Compression of protein layer, no desorption
-5
0
5
10
15
20
25
30
0.005 0.010 0.015 0.020
1/Area , cm2
P,
mN
/m
experiment
start after relax.
fit
41
Interactions of lipopolysaccharides and antennary glycine compounds in
aqueous media
Anna Gyurova, Stefan Stoyanov, Elena Mileva
Department of Interfaces and Colloids, Institute of Physical Chemistry,
Bulgarian Academy of Science, Sofia 1113, Bulgaria,
e-mail: [email protected]
Self-assembly of star-like oligomers results in nanostructures of unusual properties and
important applications (medicine, waste water purification, etc.). Some of these oligomers form stable
hydrophilic nanoplatforms in aqueous media. These platforms may serve as captive agents for
endotoxins. The aim of the present study is to perform systematic investigations on the interactions of
one type of lipopolysaccharides from bacteria Escherichia Coli with aqueous solutions of antennary
glycine compounds. Conditions for fine tuning of lipopolysaccharide capture by the glycine platforms
are outlined. The initial results are encouraging and the acquired knowledge may be applied e.g. for
controlled purification of contaminated waters.
Acknowledgements: The financial support of NSF of the Ministry of Education, Youth and Science
(Bulgaria) by Project BG 051PO001–3.3.06–0038 is gratefully acknowledged.
42
Stabilization of aqueous foams using co-surfactants
Christopher A.E. Hamlett and David J. Fairhurst
School of Science and Technology, Nottingham Trent University, NG11 8NS, United Kingdom,
[email protected], [email protected]
Aqueous foams are a common occurrence in everyday life (e.g. washing up foams) and are
stabilized by surfactants assembling at the solution-gas interface. Our work is concerned with
investigating the impact of the addition of a secondary surfactant to the surfactant solution on the
stability of the resultant foam. This poster presents the setup we use for foam generation and the
apparatus used for our stability tests along with preliminary stability experiments carried out on foam
generated from an aqueous solution of sodium lauryl ether sulphate (SLES).
43
Foam processes at VTT
Tuomo Hjelt1, Karita Kinnunen, Jani Lehmonen
1
1 VTT Technical Research Centre of Finalnd, Espoo, Finland,[email protected]
At the start of the presentation there will be short introduction of VTT (Technical Research
Centre of Finland). Then the rest of the talk will concentrate two foam processes that have been
studied lately at VTT.
Foam forming method is process where foam instead of water is used to transfer fibers to the
actual web former. At former section foam is sucked away and fiber mat is created. The advantage of
this process is that is allow wide variety of raw materials (fiber length 0.5 mm – 5 cm) and saving on
water consumption. Method also guarantees very even fiber distribution and allows making low
density structures. In this method the retention of nano particles is good and it is easy to make layered
structures.
Foam coating method is process where foam instead of water is used to transfer coating
material to the coater applicator. In this method coating particles are locked inside foam vortices, thus
preventing aggregation of the coating particles. It is especially beneficial in nano particle coating,
because it allows to make very thin coatings evenly. We have been able to make coating of nano silica
particles on paper surface, where coating thickness was 0.5 µm and particles were evenly distributed.
Method is suitable for coating of all porous materials that absorb water.
44
Exploiting the Kubas Interaction in Hydrogen Storage
Tuan K. A. Hoang2, David Antonelli
1
1 Sustainable Environment Research Center, University of Glamorgan, Pontypridd, CF37-1DL, United Kingdom,
[email protected]. 2 Department of Chemistry and Biochemistry, University of Windsor. 401 Sunset Avenue, Windsor, Ontario, N9B 3P4,
Canada, [email protected]
The use of the Kubas interaction1 in hydrogen storage is discussed, with a focus on approaching
ideal enthalpies for on-board storage and the synthetic efforts involved in designing an extended solid
without organic ligands that adsorbs and desorbs H2 using this mechanism.2,3
Thus, titanium(III)
hydrazide gels designed for Kubas-type hydrogen storage were synthesized from the reaction between
tris(bis(trimethylsilyl)methyl) titanium and anhydrous hydrazine. The materials demonstrate a fully
reversible H2 adsorption capacity of 2.63 wt% and 36.7 kg/m3 at 298 K and 143 bar without
saturation. Interaction between the adsorption center and H2 gas was probed by electron paramagnetic
resonance. Computational efforts showed a maximum adsorption of 9.9 wt% rationalized the rising
enthalpies and linear isotherms by a new mechanism involving a pressure-induced deformation of the
amorphous structure. We also show how porous Ti (III) hydride gels are a promising new hydrogen
storage medium, exploiting the first example of a solid state hypervalent metal hydride. This was
accomplished using weak chemisorption to a Ti (III) hydride framework with binding enthalpies in
the 15-30 kJ/mol range, predicted to be ideal for use in a room temperature hydrogen storage system.
These materials use bridging hydride ligands as an ultra-lightweight structural feature to support a
microporous network of Ti binding sites for molecular H2 chemisorption. High-pressure Raman
spectroscopy confirmed the first evidence of hypervalent Ti hydride species with Kubas-type
dihydrogen ligands. The material with the highest capacity has an excess reversible storage of 3.49
wt % at 140 bar and 298 K without saturation, corresponding to 44.3 kg/m3 of volumetric density,
comparable to the DOE 2017 volumetric system goal of 40 kgH2/m3. By extrapolation, removal of
all hydrocarbon from this material would lead to storage capacities of over 6 wt% at pressures under
150 bar without any kinetic or thermodynamic problems.
1Hoang, T. K. A. & Antonelli, D. M. (2009): Exploiting the Kubas Interaction in the Design of Hydrogen Storage Materials.
Adv. Mater. 21, 1787.
2Hoang, T. K. A., Webb, I. M., Mai, H. V., Hamaed, A., Walsby, C. J., Trudeau, M. & Antonelli, D. M. (2010): Design and
Synthesis of Vanadium Hydrazide Gels for Kubas-Type Hydrogen Adsorption: A New Class of Hydrogen Storage
Materials. J. Am. Chem. Soc. 132, 11792.
3Hamaed, A., Hoang, T. K. A., Moula, G., Aroca, R., Trudeau, M. & Antonelli, D. M. (2011): Hydride-Induced
Amplification of Performance and Binding Enthalpies in Chromium Hydrazide Gels for Kubas-Type Hydrogen Storage. J.
Am. Chem. Soc. 133, 15434.
45
New modules for automised foam characterisation in the FoamScan
Clément Honorez1, Alain Cagna
2, Wiebke Drenckhan
1, Emmanuelle Rio
1, Dominique
Langevin 1, Anniina Salonen
1
1. Laboratoire de Physique des Solides, Université Paris Sud, UMR 8502,Orsay, France [email protected]
2. Teclis, Longessaigne, France
The FoamScan (Teclis), is an automated device to analyse the generation and stability of
foams. Since foams are in general turbid media, the determination of the bubble size is difficult. Thus,
in most cases, images are taken at the surface of the container. However, it is not clear whether the
cell size distribution at the surface is really representative of that in the volume.
To overcome this problem, we are developing two new modules for the FoamScan which
allow to obtain information about the evolution of the bubble size. On the hand, this is done via the
scattering of white light which relies on the strong link between light transmission, liquid fraction and
size of bubbles in a foam. On the other hand, we implement automated investigations of 2D Foams
(monolayers of bubbles between plates) using a cell with small plate spacing. This module measures
foam conductivity, the height of foam and the size of the bubbles. The two modules extend the
possibilities of automated foam characterization and open doors to further foam science.
Figure 1: Left: 2D foams module; Right: shaving foam by white light scattering
46
Nanoparticles characterization by a non-intrusive measurement
technique
I. Horvath1, P. Colinet
2, J. B. Gouriet
1 and M. R. Vetrano
1
1 Institut Von Karman, 1640 Rhode-Saint-Genèse, Belgium, [email protected]
2 Université libre de Bruxelles, TIPs department, CP 165/67, 1050 Bruxelles, [email protected]
Because of the large interest in nanoparticles and nanoparticles flows, there is a strong need for
online submicron particle characterization techniques. In this framework the Multi Wavelength Light
Extinction (MWLE) technique, which is a non-intrusive optical technique for nanoparticles size and
concentration measurement, is developed. Its operation relies on the measurement of the spectral
transmittance of a light beam. The transmittance spectrum depends on the size and concentration of
the investigated particles. Therefore, the underlying particle size distribution and concentration can be
retrieved after the inversion of an appropriate light scattering model. The inverse light scattering
problem turns out to be a highly ill-conditioned problem, hence requiring a specific regularized
inversion algorithm for the retrieval of the underlying Particle Size Distribution function from the
measurement data. In this presentation the most appropriate regularization method to solve the
inversion problem will be discussed [1]. An experimental apparatus, allowing simultaneous
measurements with the MWLE technique and a Scanning Mobility Particle Sizer (intrusive probe),
has also been built for the purpose of validation. Measurements are performed with a Potassium
Chloride (KCl) solid particles aerosol. It is shown that, in typical experimental conditions, the
measurement of the particle size with the two instruments is in satisfactory agreement with a
maximum discrepancy of 10% [2]. The development of this technique gives rise to a large amount of
applications, going from the measurement of nanoparticles in plasmas or in more complex
environments, to the measure of self-assembled structures which are formed on the surface of a thin
evaporating liquid film containing nanoparticles. For the latter application, the presence of the liquid-
gas interface is expected to influence the accuracy of the MWLE measurements and a light scattering
model, which is capable to account for the presence of an interface, is currently in development.
Figure 1 Comparison of SMPS and MWLE distribution obtained for a KCl nanoparticles flow
1 I. Horvath and M. R. Vetrano, “Development of the Multi Wavelength Light Extinction technique for size and
concentration measurements of nanoparticles”, presented at the Lasers and nteractions with Particles Workshop, NSA de
Rouen, CORIA UMR 6614, Rouen, France.
2 I. Horvath, E. Pescini, P. Colinet and M. R. Vetrano, “Application de la technique spectroscopique d’extinction à un
écoulement de nanoparticules”, in Proceedings of the 13ième Congrès Francophone de Techniques Laser, CFTL 2012 -
ROUEN, 18 – 21 Septembre 2012.
47
A Front-Tracking Method for Computational Modeling of Viscoelastic
Two-Phase System
Daulet Izbassarov1, Ufuk Olgac
2 and Metin Muradoglu
3,*
1,3Department of Mechanical Engineering, Koc University, Rumelifeneri Yolu, Sariyer 34450, Istanbul, Turkey 2Institute of Physiology, University of Zurich, Zurich, Switzerland
*E-mail: [email protected]
A front-tracking method has been developed for direct numerical simulations of viscoelastic
two-phase systems including motion of Newtonian droplets/bubbles in a viscoelastic fluid,
viscoelastic droplets in a Newtonian fluid, viscoelastic droplet in a viscoelastic fluid and Newtonian
droplets/bubbles in a Newtonian fluid. Following Unverdi and Tryggvason1, one set of governing
equations is written for the whole computational domain and different phases are treated as a single
fluid with variable material and rheological properties. The interface is tracked explicitly using a
Lagrangian grid while the flow equations are solved on a fixed Eulerian grid. The surface tension is
computed at the interface using the Lagrangian grid and included into the momentum equation as a
body force. The FENE-CR model of Chilcott and Rallison2,3
is employed to model the viscoelasticity.
The FENE-CR model equations are solved coupled with the flow equations using an explicit scheme
suggested by Sarkar and Schowalter4.
The numerical algorithm is first tested for a single-phase viscoelastic fluid flow through an
abrupt axisymmetric 4:1 contraction and the results are compared with the computational simulations
of Coates et al. 2. It is found that the present results are in a very good agreement with computational
simulations of Coates et al.2 both qualitatively in terms of streamline patterns and quantitatively for all
flow variables including the mean velocity and the extra stress components at various cross sections.
The method is then applied to study fluid dynamics of buoyancy-driven viscoelastic two-phase
systems in a capillary tube. This problem was
recently studied computationally by You et al.5.
Extensive computations are performed to
examine the effects of confinement, material
properties, and rheological properties of the two
phases on drop mobility and deformation.
Sample preliminary simulation results are plotted
in Fig. 1 for Newtonian drop in a viscoelastic
fluid and a viscoelastic drop in a Newtonain
fluid. The preliminary results show that a
Newtonian drop immersed in a viscoelastic fluid
experiences an extending trailing edge, while a
viscoelastic drop in a Newtonian fluid develops
an indentation around the rear stagnation point.
These preliminary results are consistent with the
computational simulations of You et al.5.
1 Unverdi, S.O., Tryggvason, G. (1992): A front-tracking
method for viscous, incompressible, multi-fluid flows. J. Comput. Phys. 100(1):25-37.
2Coates, P. J., Armstrong, R. C., Brown, R. A. (1992): Calculation of steady-state viscoelastic flow through axisymmetric
contractions with the EEME formulation. J. Non-Newtonian Fluid Mech., 42:141-188.
3Chilcott, M. D., Rallison, J. M. (1988): Creeping flow of dilute polymer solutions past cylinders and spheres. J. Non-
Newtonian Fluid Mech., 29:381-432.
4Sarkar, K., Schowalter, W. R. (2000): Deformation of a two-dimensional viscoelastic drop at non-zero Reynolds number in
time-periodic extensional flows. J. Non-Newtonian Fluid Mech., 95:315-342.
5You, R., Haj-Hariri, H., Borhan, A. (2009): Confined drop motion in viscoelastic two-phase systems. Phys. Fluids,
21, Art. No. 013102.
Fig. 1: Steady drop shapes with the velocity vectors (left
side) and the contours of extra stress tensor component τθθ
(right side) in the vicinity of a buoyancy-driven droplet.
(a) A Newtonian droplet rising in a viscoelastic fluid. (b)
A viscoelastic droplet rising in a Newtonian fluid.
48
Nanostructuring of bulk Mg and its alloys via severe plastic deformation
Aleš Jäger1, Erik Švec
1, Jan Duchoň
1, Viera Gärtnerová
1
1 Department of Advanced Structural Materials, Institute of Physics, Prague, Czech Republic, [email protected]
Equal channel angular pressing (ECAP) has been shown to be an effective tool for grain
refinement in bulk Mg and various Mg alloys resulting in improved properties. In most investigations,
however, the processing temperature was at or above 200°C to avoid cracking that, in turn, suppress
refinement due to grain growth.
In this work, magnesium and selected binary magnesium alloys were processed by equal
channel angular pressing with back pressure (ECAP-BP) at room temperature (RT) in order to obtain
a material with excess of defects and/or fine-grained microstructure. Microstructure was examined by
scanning electron microscope (SEM), electron backscatter diffraction (EBSD), X-ray diffraction
(XRD) and transmission electron microscopy (TEM). Microstructural stability was investigated by
dilatometry and static annealing. It is shown that multiple ECAP passes with back pressure at room
temperature results in crack-free structure with ultra-fine grains and with abundant concentration of
defects.
The aim of this presentation is to show current possibilities of microstructural refinement of
bulk magnesium and its alloys via severe plastic deformation (ECAP-BP) at RT.
49
Metal droplet detachment regimes in
ring cross-section conical laser beam droplet generation
Andrej Jeromen1, Edvard Govekar
1
1 Laboratory of Synergetics, Faculty of Mechanical Engineering, University of Ljubljana, Ljubljana, Slovenia,
Metal droplets can be applied in various manufacturing applications related to droplet joining
and 3D structuring. The core process of these applications is a novel laser droplet generation process
where the tip of the vertically fed metal wire is melted by a ring cross-section conical laser beam. The
critical phase in laser droplet generation is droplet detachment. It has been observed that beside the
numerous process variables, the droplet formation process and droplet detachment are governed by
the interaction between the laser pulse frequency and the dynamics of pendent droplet. Depending on
the laser pulse frequency, three different detachment regimes accompanied by different dynamics
have been identified: a) spontaneous dripping, caused by the force of gravity alone, b) resonant
detachment, caused by a combination of the gravity force and the laser induced oscillation modes of
the pendant droplet, and c) break-up caused by the Rayleigh-Plateau instability.
50
On the identification of liquid surface properties using liquid bridges
Thodoris D. Karapantsios1, Margaritis Kostoglou
2
1 School of Chemistry, Aristotle University of Thessaloniki, email:[email protected] 2 School of Chemistry, Aristotle University of Thessaloniki, email:[email protected]
The term liquid bridge refers to the specific silhouette of a liquid volume when it is placed
between two solid surfaces. Liquid bridges have been studied extensively both theoretically and
experimentally during the last century due to their significance in many technological applications. It
is worth noticing that even today new technological applications based on liquid bridges continue to
appear. A liquid bridge has a well-defined surface configuration dictated by a rigid theoretical
foundation so the potential of its utilization as a tool to study surface properties of liquids is apparent.
However, it is very scarce in literature that the use of liquid bridges is suggested as an alternative to
the other well-established drop techniques. The present work presents the theoretical background to
setting up the liquid-bridge based surface property estimation problem, describes the required
experimental equipment and performs a thorough literature review on the subject. A case with
particular interest is that of liquid bridges made of conducting liquids that connect two conducting
solids; such a liquid bridge presents electrical conductance which is sensitive to the specific silhouette
of the bridge. This enables the use of their conductance as shape descriptor instead of the conventional
image processing techniques. Several attempts in the literature for the estimation of the liquid surface
tension, liquid-solid contact angle and surfactant induced surface elasticity for conducting or
non/conducting liquids are presented and the prospects of the technique are discussed.
51
Deposition of solid particles at streamlined surface in turbulent flow
Alexander Kartushinsky, Medhat Hussainov, Igor Shcheglov, Ylo Rudi, Sergei Tisler
Research Laboratory of Multiphase Media Physics, Tallinn University of Technology, Tallinn, Estonia,
Deposition of corundum 12 and 23 µm particles onto horizontal flat plate within the laminar
boundary layer in the free-stream moderate turbulent flow was studied. The presented numerical
model considered the deposition onto the surface to be probabilistic process determined both by
hydrodynamics and the adhesive behavior of particles and surface.
Numerical simulation was realized under the conditions of the laminar boundary layer. The two
fluid approach was used for writing Euler-Euler equations for carrier gas and particulate phase.
Effects of gravity and lift forces on particles velocities and mass concentration, occurring
within the boundary layer, and deposition were studied separately for various particle sizes.
It was revealed that gravity and lift forces have decisive influence on behavior of solid particles
taken place within the laminar boundary layer and on their deposition, that is expressed via the
distributions of the particles transversal velocity and mass concentration. These effects become more
pronounced for the larger 23 µm particles.
The given study is the attempt to combine the hydrodynamic and adhesive aspects of the
particles deposition for its more accurate estimate, that is suitable for various practical devices.
52
Turbulent particulate pipe flow at constant Reynolds number
Alexander Kartushinsky1, Efstathios Michaelides
2, Ylo Rudi
1, Sergei Tisler
1
1 Research Laboratory of Multiphase Media Physics, Tallinn University of Technology, Tallinn, Estonia,
[email protected] 2 Department of Engineering, Texas Christian University, Fort Worth, TX, USA, [email protected]
Effect of the pipe diameter was numerically investigated in the particulate turbulent cylindrical
pipe flows at constant Reynolds numbers. The method used is based on 2D Reynolds-averaged
Navier-Stokes equations. This approach is supplied with closure equations allowing all pertinent
forces and effects: particle-particle, particle-wall, particle-turbulence interactions, gravitation, viscous
drag and lift forces and turbulence modulation. Finite volume technique was applied for numerical
solution of governing equations.
Results show the effect of the pipe diameter, flow mass loading and particles size on the radial
distributions of the velocity lag, turbulence modulation and particles concentration. In particular,
increase of the pipe diameter at constant Reynolds number results in decrease of the relative velocity
lag and flattening of the radial distributions of particles velocity and mass concentration as well as
decrease of a turbulence attenuation rate.
The present model with applying of minimum number of assumptions represents a more
contemporary computational approach in turbulent particulate flow.
53
Emulsification of oil in a shear-thickening fluid
Jaroslav Katona, Sandra Njaradi, Verica Sovilj, Nikola Mičić, Lidija Petrović
Faculty of Technology, University of Novi Sad, Novi Sad, Serbia, [email protected]
Emulsification of oil in a shear-thickening continuous phase was investigated. The continuous
phase was a mixture of 0.7% w/w hydroxypropylmethyl cellulose (HPMC), a nonionic derivative of
cellulose, and 0.00-2.00% w/w of sodium dodecylsulfate (SDS), an anionic surfactant. HPMC-SDS
complex formation takes place in the continuous phase when SDS concentration is higher than the
critical association concentration (cac=0.15%) 1, 2
. SDS concentration influences rheological behavior
of the continuous phases. When SDS concentration is between 0.35-1.25% w/w a characteristic shear
thinning viscosity profile is disrupted at shear rates exceeding a critical one. Above the critical shear
rate, which depends on SDS concentration, shear thickening is observed, indicating shear-induced
structure formation in the system. Emulsions of paraffin oil (5% v/v) in continuous phases of different
HPMC/SDS composition were prepared by microfluidzer (M-5000, Microfluidics, USA). Dispersion
and rheological properties of the emulsions were tested and were found to be influenced by
HPMC/SDS interaction. Emulsions with submicron droplet sizes were obtained when SDS
concentration was >0.35% w/w i.e. when shear-induced structure formation took place in the
continuous phase of an emulsion. Viscosity of emulsions was found to be lower than that of
corresponding continuous phases.
1 Katona, J. M., Sovilj V. J. (2008): Rheological investigation on dynamics and structure of separated phases in polymer-
mixture – ionic surfactant ternary mixtures. Carbohydrate Polymers 74, 193-200.
2 Picullel, L., Egermayer, M., Sjostrom, J. (2003): Rheology of mixed solutions of an associating polymer with a surfactant.
Why are different surfactants different? Langmuir 19, 3643 - 3649.
54
Uniform, adhesive, robust Cu/TiO2 films inducing eco-friendly
bacterial/viral inactivation under low intensity solar light
J. Kiwi*, Sami Rtimi*, Cesar Pulgarin
*, R. Sanjines‡
*Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015, Lausanne, Switzerland
‡Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-IPMC-LNNME, Bat PH, Station 3, CH-1015,
Lausanne, Switzerland
This study reports the sputtering of Cu1-3
and TiO2/Cu4-5
films on textile by conventional pulsed
direct current magnetron sputtering (DCP) and highly ionized pulsed plasma magnetron sputtering to
inactivate E. coli (Gram-negative) and methicillin resistant staphylococcus aureus (MRSA, Gram-
positive) within short times. Uniform films were obtained with suitable adhesion to the substrate and
can be used in a repetitive way to inactivate bacteria at the solid-air interface. Low intensity sunlight
with an intensity of 0.5-1% AM1 and actinic light (400-700 nm, with light dose < 1 mW/cm2)
accelerate the bacterial inactivation. This is important when precluding the formation of biofilms
pumping infectious bacteria in hospitals, schools and other public places since they are active for long
time as a source of pathogens. Surface characterization of the films is presented using X-ray
fluorescence (XRF), profilometry, electron microscopy (HRTEM) and X-ray photoelectron
spectroscopy (XPS). By highly ionized pulsed plasma magnetron sputtering (HIPIMS) due to the
increased M+-ions energy and the high charge density of ~10
18-19 e-/m
3, a coating ~38 nm thick
inactivated E. coli within 10 minutes when using a TiO2 60/Cu 40 atomic percent target. DCP
sputtering inactivated bacteria within similar times but a coating ~ 600 nm thick was required to attain
similar bacterial inactivation kinetics.
Using a TiO2 60/ Cu 40 atomic percentage target in the dark samples sputtered by HIPIMS for
150s induce a slow bacterial inactivation within 120 min showing the Cu-inactivation properties.
Under actinic light radiation, samples deposited by pulsed magnetron sputtering time of 150s induced
short inactivation times of ~10 min. This sample presents the most suitable structure-reactivity for the
Cu-clusters on the TiO2. The bactericide action under light is due to a synergic effect in the TiO2/Cu
layers since longer inactivation times were observed when sputtering TiO2 or Cu separately. The
HIPIMS sputtered TiO2/Cu film presenting a thickness of ~38 nm required ~10 min to inactivate E.
coli. By comparison DCP films with a thickness of 600 nm required ~6 min to inactivate bacteria.
DCP sputtering leads to M+ ionization >>5% and a charge density ~10
16 e-/m
3 But HIPIMS
leads to Cu ionization of ca. 70% with a charge density ~1018-19
e-/m3 and with a power per pulse of
1750 W/100 microseconds compared to the DCP power per pulse of 62.3 W/pulse. The effective
antibacterial thin film action by the HIPIMS films were possible due to the applied higher applied
since a higher V increases the transition M M+.
1 Osorio, P., Sanjines, R., Ruales, C., Castro, C., Pulgarin, C., Rengifo, J-C., Lavanchy, Kiwi, J. (1995): Antimicrobial Cu-
functionalized surfaces prepared by bipolar asymmetric DC-pulsed magnetron sputtering (PMS). J. Photochem. Photobiol. A
220, 70-76
2 Ehiasarian, A., Pulgarin, C., Kiwi, J. (2012): Inactivation of bacteria under visible light and in the dark by Cu-films.
Advantages of Cu-HIPIMS sputtered films Env. Sci. Pollut. Res. 19, 3791-3797.
3 Rio, L., Kusiak, E., Kiwi,J., Pulgarin, C., Trampuz C., Bizzini, A. (2012): Comparative methods to evaluate the bactericidal
activity of copper-sputtered surfaces against methicillin-resistant Staphylococcus aureus J. Appl. Microbiol, in press, 2012.
4 Baghriche, O., Sanjines, R., Pulgarin, C., Rtimi, S., Kiwi, J. (2013): Effect of the spectral properties of TiO2, Cu, TiO2/Cu
sputtered films on the bacterial inactivation under low intensity actinic light, Photochem. Photobiol. A. 251, 50-56.
5 Rtimi, S., Baghriche, O., Pulgarin, C., Sanjines, R., Kiwi, J. (2012): Innovative TiO2/Cu surfaces inactivating bacteria <5
min under low intensity visible/actinic light TiO2/Cu surfaces, ACS Appl. Mater. & Interf. 4, 5234-5240.
6 S. Rtimi, O. Baghriche, C. Pulgarin, J-C Lavanchy, J. Kiwi, manuscript in preparation.
55
Research of materials for hydrogen generation in electrolysis and
photoelectrolysis processes
Janis Kleperis, Martins Vanags, Gunars Bajars, Liga Grinberga, Ainars Knoks, Julia Hodakovska
Institute of Solid State Physics, University of Latvia; Riga, LV-1063, Latvia; [email protected]
Surface modification of steel electrode is investigated to enhance electrolysis process for
hydrogen production. Different surface modification methods are compared. Electrode aging process
is achieved with prolonged direct current polarization of electrode, electrode cycling with high
voltage pulses, and thermal treatment in reducing atmosphere. Raney nickel coating is used to protect
steel electrode from corrosion and activate hydrogen evolution reaction on it. Analysis of volt-
amperic curves is used to compare electrode suitability for water splitting in electrolysis process.
Nanosize powder materials and coatings are tested for application in photo-activated water splitting.
Transition metal nitrides and titanium tetrabutoxide are used to obtain thin films of ferrite, titania and
mixed ferrite/titania films in spray pyrolysis method. Photo-electrochemical methods are used to
investigate photo-activity of sintered powders and thin films, structure and morphology are tested
with XRD and microscopically.
56
Influence of n-octanol on the bubble bouncing and coalescence time at
solution surface
Dominik Kosior1, Jan Zawala
1, Kazimierz Malysa
1
1Jerzy Haber Institute of Catalysis & Surface Chemistry, Polish Academy of Sciences, Krakow, Poland,
Bubble motion, collision with liquid/gas interface and coalescence are important processes in
many industrial applications, i.e. foam formation, froth flotation, aeration of water tanks etc.
Outcome of the bubble collisions depends on many mutually interconnected factors such as: bubble
size, the bubble impact velocity and shape deformations, the collision contact time, presence and state
of adsorption layer at the interacting surfaces, size and stability of the liquid film formed, surfactant
adsorption kinetics and drainage velocity of the liquid films formed, etc. It was showed earlier1,2
that
even in the case of pure liquids the coalescence of a bubble at free surface does not have to take place
during the first collision because of the bubble bouncing, which occurs when the collision contact
time is shorter than the time needed for the film formed to drain to its critical thickness of rupture.
In the present work, influence of n-octanol concentration on the bubble impact velocity,
bouncing at the solution surface and stability of the films formed by the colliding bubble is
investigated using a high-speed camera (1040 frames per second). The bubble impact velocity,
number of the bouncing and the bouncing amplitudes were measured as a function of n-octanol
concentration. As the entire lifetime of the colliding bubble consists of the time of bouncing (tb) and
lifetime of the film formed (tfilm), so these both components of the bubble coalescence time (tc=tb+tfilm)
were measured. At low n-octanol concentration the bubble impact velocity (Uimp) decreases rapidly,
but at c 3·10-5
M starts to be practically constant (ca. 15 cm/s), what indicates that at concentrations
of 3·10-5
M and higher the fluidity of the bubble surface was completely retarded3. In distilled water
(Uimp= 34.7 cm/s), where the bubble bounced 3 times and ruptured during the 4th collision the bubble
bouncing time, the tb, was equal 72 ms, while the film lifetime, tfilm, was only ca. 2-3 ms, i.e. the
bubble coalescence time was determined by the bubble bouncing. With increasing n-octanol
concentration the film lifetime increases rapidly and therefore starts to be the parameter determining
the bubble coalescence time. For example, at very low n-octanol concentration 6·10-6
M
(Uimp= 24.8 cm/s) the bouncing time was similar as in water (tb=76 ms) but the coalescence time was
immensely prolonged - to ca. 1100 ms. In 1·10-3
M n-octanol solution the bubble coalescence time
was of an order 3·104
ms (30 s), while the bouncing time was shortened to 13 ms only - lower bubble
impact velocity, Uimp= 15 cm/s. These data also show clearly that stability of the liquid film formed
determines process of the foam layer formation - the foam layer can be formed when the film lifetime
is longer than the time interval between subsequent bubbles arriving at the solution surface.
1 Krzan, M., Lunkenheimer, K., Malysa, K. (2003): Pulsation and Bouncing of a Bubble Prior to Rupture and/or Foam Film
Formation. Langmuir 19, 6586-6589.
2 Zawala, J., Malysa, K. (2011): Influence of the Impact Velocity and Size of the Film Formed on Bubble Coalescence Time
at Water Surface. Langmuir 27, 2250-2257.
3 Malysa, K., Zawala, J., Krzan, M., Krasowska, M., „Bubbles Rising in Solutions Local and Terminal Velocities, Shape
Variations and Collisions with Free Surface”, in “Bubble and Drop Interfaces” (R. Miller, K. Liggieri – Eds), Brill
Publishers, Leiden Boston 2011, chap. XI, pp. 243-292.
57
Rheology of particlepolymer gels subjected to
compression by centrifugation
Elena K. Kostova,1 Theodor D. Gurkov,
1 Wolfgang Gaschler
2
1 Department of Chemical Engineering, University of Sofia, Faculty of Chemistry & Pharmacy,
James Bourchier Avenue 1, Sofia 1164, Bulgaria, [email protected] 2 BASF SE, 67056 Ludwigshafen am Rhein, Germany
We study the creaming stability of aqueous dispersions whose particles consist of solid fatty
alcohols, and have sizes of a few µm. High stability against thickening is provided by polymers
(polyacrylamide, PAM, and polyacrylic acid, PAA). Centrifugation is performed in multiple steps,
each one with fixed time duration, in two ways: either with increasing rotation speed, or at one and
the same rotation speed. The (average) volume fraction of particles in the cream, , is determined
from the amount of separated cream. The pressure dependence of gives information about the
structure of the compressed dispersion1 specifically, the density, degree of homogeneity, size of
voids. The change of as a function of time, at fixed acceleration, shows a typical linear dependence
(Fig. 1). The latter is related to a viscous-type drainage of liquid from the structure. The slope of the
(t) plot increases with the rotation speed, in agreement with the expected trend, 2/ dtd . We
discuss the influence of different factors on the creaming stability, such as the concentration of the
polymers, the ratio between PAM and PAA, presence of small hydrophilic particles (Bentonite), etc.
The interparticle contacts are much stronger with PAA, as compared to the case with PAM.
(a)
(b)
(c)
Figure 1. Structure of dispersions: (a), (b); Cream compaction at low rotation speed: (c).
Information about the extent of irreversible flocculation is gained from experiments with
redispersion of the cream and subsequent centrifugation, combined with microscopic observations.
When stiff aggregates cannot repack tightly, the volume fraction ‹› remains quite low.
1 Wyss, H. M., Tervoort, E. V., Gauckler, L. J. (2005): Mechanics and microstructures of concentrated particle gels.
J. Amer. Ceram. Soc. 88(9), 2337-2348.
Acrylic acid (PAA, 0.1%) + Acrylamide (PAM, 0.1%)
y = 1.425E-04x + 2.234E-01
y = 1.026E-04x + 2.236E-01
y = 6.756E-05x + 2.291E-01
0.210
0.230
0.250
0.270
0.290
0.310
0 60 120 180 240 300 360 420 480 540 600 660
time, min
Wa
x v
olu
me
fra
cti
on
in
cre
am
, ‹ φ
›
0.215
0.235
0.255
0.275
0.295
0.315
600 rpm
600 rpm-Lin.
500 rpm
500 rpm-Lin.
400 rpm
400 rpm-Lin.
58
Mechanical Properties of films of self-crosslinked latexes based on
copolymers BA/MMA/DAAM or BA/MMA/VEOVA-10/DAAM with
adipic acid dihydrazide
Christos Koukiotis 1, Maria M. Karabela
2, Irini D. Sideridou
2
1 LOUFAKIS CHEMICALS SA, THESSALONIKI, GREECE, [email protected]
2 Laboratory of Organic Chemical Technology, Department of Chemistry, Aristotle University of Thessaloniki,
Thessaloniki, Greece
The MFFT (Minimum Film Forming Temperature) and the mechanical properties of self-
crosslinked latexes based on copolymers butyl acrylate (BA)/ methyl methacrylate (MMA)/ diacetone
acrylamide (DAAM) and BA/MMA / vinyl neo-decanoate (VEOVA-10)/DAAM were measured
using the adipic acid dihydrazide (ADH) as crosslinking agent inside the latex.
The surface hardness and the static tensile strength of films were improved in all cases by the
addition of the crosslinking agent ADH. Also the use of polymerizable emulsifier during the
preparation of the latexes caused an impressive improvement of mechanical properties of the films, in
comparison with mechanical properties of the films of latexes which prepared without polymerizable
emulsifiers. In the majority of the experiments the addition of ADH caused also clear reduction of the
MFFT.
Over and above in our previous publication1 we found also that the films of the self-crosslinked
latexes prepared with the polymerizable emulsifier and ADH showed very good performance in
measurements of gloss, water absorption, swelling in butanone. This makes them ideal binder for 1K
high performance green coatings that are friendly to the environment and safe to use. The surface
tensions of these latexes are relative high due to the fact that most of the surfactant copolymerizes
with the monomers. We intent to study the influence of several additives in interfacial tension
measurements and measurements of interfacial viscosity and elasticity in a broad range of conditions
as close as possible to those met in practice.
1 Christos Koukiotis, rini D. Sideridou, (2010): “Synthesis and characterization of latexes based on copolymers BA MMA
DAAM and BA MMA VEOVA-10 DAAM and the corresponding 1K crosslinkable binder using the adipic acid
dihydrazide as crosslinking agent”, Progress in Organic Coatings 69, 504.
59
Poly(ethylene oxide)-based structures self-assembled on surfaces
after evaporation from aqueous solutions
Vasileios Koutsos, Dimitrios Mamalis, Michail Kalloudis and Khellil Sefiane
nstitute for Materials and Processes, School of Engineering, The niversity of Edinburgh, King’s Buildings, Mayfield
Road, Edinburgh EH9 3JL, United Kingdom, [email protected], [email protected]
Polyethylene oxide (PEO)-based thin films and structures have important biomedical
applications as PEO is biocompatible and exhibits protein resistance1. One of the unique attractions of
PEO (which is related to its biomedical properties) is its water solubility2 which provides
opportunities for environmentally-friendly fabrication, based on self-assembly, of advanced (and
potentially ‘smart’) thin films and structures at several scales.
Firstly, we present an atomic force microscopy (AFM) study of the nano/microstructure
morphology of pure PEO thin films spin cast on mica from aqueous solutions. Then, we continue with
a comprehensive investigation of a series of amphiphilic poly(isoprene-b-ethylene oxide) diblock
copolymer thin films (with various block fractions) fabricated in the same manner. We show the
crucial effect of the PEO crystallization in determining the morphology of the self-assembled
structures. We also give examples of potential ‘smart’ use of these nano/microstructures as responsive
surfaces to environmental conditions.
In the second part of the presentation, we concentrate on the fabrication of larger (mm-sized)
PEO structures. We used drying droplets of PEO solutions (several molecular weights of PEO) to
study in some depth the pinning/de-pinning transition which is a determining factor for the final
morphology of the deposit (this process can lead to pillar formation3,4
under specific conditions). The
nano/microscopic contact line phenomena are presented and discussed.
1 Liu, V. A., Jastromb, W. E., Bhatia, S. N. (2002): Engineering protein and cell adhesivity using PEO-terminated triblock
polymers. Journal of Biomedical Materials Research 60 (1), 126-134.
2 Dormidontova, E. E. (2001): Role of Competitive PEO−Water and Water−Water Hydrogen Bonding in Aqueous Solution
PEO Behavior. Macromolecules 35 (3), 987-1001.
3 Willmer, D., Baldwin, K. A., Kwartnik, C., Fairhurst, D. J. (2010): Growth of solid conical structures during multistage
drying of sessile poly(ethylene oxide) droplets. Physical Chemistry Chemical Physics 12 (16), 3998-4004.
4 Baldwin, K. A., Granjard, M., Willmer, D. I., Sefiane, K., Fairhurst, D. J. (2011): Drying and deposition of poly(ethylene
oxide) droplets determined by Peclet number. Soft Matter 7 (17), 7819-7826.
60
Dynamic interactions of selected mineral nanoparticles
with the pulmonary surfactant at the air/water interface
Katarzyna Kramek-Romanowska, Tomasz R. Sosnowski
Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw; [email protected]
Mineral nanoparticles (NPs) may be extensively inhaled in different environments, also in the
workplace (e.g., production of nanocomposites where NPs are used as fillers to novel polymers).
Following inhalation, NPs are deposited inside the lungs on the surface of alveolar liquid where the
pulmonary surfactant (PS) forms a barrier between external environment and lung tissue. Interactions
between these nanoparticles and the surfactant may be responsible for adverse health effects as it is
well recognized that dynamic surface activity of PS is important for the vital lung functions1.
In this study we evaluate the impact of selected mineral NPs on dynamic surface activity of
animal-derived PS (Survanta) at the air/water interface by application of bubble pressure method (BP2
tensiometer, Krüss). Measurements were done at physiological temperature for NPs of natural
aluminosilicates (halloysite and bentonite) and of three types of surface-modified montmorillonites
(SMM). Particle properties (size, morphology and surface area) were tested during our earlier
works2,3
. Concentrations of nanoparticles in the surfactant solution were estimated from calculations
of deposited particle mass after breathing with dust-contaminated air3. It was found that all tested
nanoparticles change the dynamics profiles of the surface tension at the air/water interface, but the
effect is strongly dependent on particles properties and their concentration (Fig.1 & 2). For surface-
modified NPs there is an initial increase in the dynamic surface activity, and this effect well
corresponds to our previous findings from the measurements with oscillating bubble technique3. The
results indicate that mineral NPs change the dynamic surface tension of the pulmonary surfactant and
this effect may be related to certain health effects in the respiratory system after inhalation of NPs.
1Sosnowski T.R., radoń L., Podgórski A. (2000): nfluence of insoluble aerosol deposits on the surface activity of the
pulmonary surfactant: a possible mechanism of alveolar clearance retardation ? Aerosol Sci Techn 32, 52-60.
2Kondej D., Sosnowski T.R. (2012): Changes in the activity of the pulmonary surfactant after contact with bentonite
nanoclay particles. Chem Eng Transact 26, 531-536.
3Kondej D., Sosnowski T.R. (2013): Alteration of biophysical activity of pulmonary surfactant by aluminosilicate
nanoparticles. Inhalation Toxicol (accepted)
Fig. 1. Dynamic surface tension of pulmonary surfactant Fig.2. Dynamic surface tension of pulmonary surfactant
(Survanta) in the presence of bentonite nanoparticles. (Survanta) in the presence of SMM nanoparticles.
Acknowledgements: Work done under umbrella of COST action MP1106
as a part of statutory activity of the Faculty of Chemical and Process Engineering.
61
Effect of operating pressure and electrode surface roughness on gas-
liquid flow patterns in thin-gap electrochemical microreactor
Jiri Kristal, Petr Stavarek, Petr Zaloha and Vladimir Jiricny
Institute of Chemical Process Fundamentals, Czech Academy of Sciences, Prague, Czech Republic, [email protected]
Application of a thin-gap electrochemical microreactor (EMR) for intensification of the electro-
organic synthesis has been recently investigated by our group1,2
. In the studied thin-gap EMR, the
inter-electrode gap is only 0.1 mm while the microchannel width is 10 mm, so the microchannel has
an extremely low aspect ratio of 0.01. This arrangement is particularly interesting for the applications
with the low-conductivity electrolytes as it minimizes the ohmic drop between the electrodes.
This contribution reports on the experimental investigation of the effect of the operating
pressure and electrodes surface roughness on gas-liquid flow in the thin-gap electrochemical
microreactor. For description of gas-liquid flow in the microreactor two hydrodynamic characteristics
were selected: flow pattern and bubble size distribution. Experimental data obtained by visualization
of gas-liquid flow in microreactor were evaluated by image processing using Matlab Image
Processing Toolbox. Our results show that in a thin-gap microreactor the four distinct flow patterns
may exist. Namely, the flow without bubbles, dispersed bubbly flow, bubbly flow and churn flow
were observed. Presented flow maps indicate the conditions for the respective flow pattern. Results of
bubble size distribution confirmed the expected trends; with increasing liquid flow rates the bubble
size decreases, and with increasing current density, bigger bubbles are generated. Utilization of the
electrodes with lower surface roughness resulted in bigger bubbles, whereas coarser electrodes
generated more uniform flow of smaller bubbles. Operating pressure had a dominant effect on bubble
size. Already at operating pressure of 1 bar, the electrochemically preferred dispersed bubbly flow
was observed for wider range of operating conditions when compared to the atmospheric operation.
The effect of operating pressure was significantly stronger than the effect of electrode surface
roughness, and appears very promising from the application point of view.
1 Kristal, J., Kodym, R., Bouzek, K., Jiricny, V. (2008): Electrochemical microreactor and gas-evolving reactions.
Electrochemistry Communications 10, 204-207.
2 Bouzek, K., Jiricny, V., Kodym, R., Kristal, J. and Bystron, T. (2010): Microstructured reactor for electroorganic synthesis.
Electrochimica Acta 55, 8172-8181.
62
Local particle–free-surface interaction
causes global particle accumulation
Hendrik C. Kuhlmann1, Roman Mukin
1,2
1 Institute of Fluid Mechanics and Heat Transfer, Vienna University of Technology, Austria,
mailto:[email protected] 2 Paul Scherrer Institute, Villingen, Switzerland, mailto:[email protected]
Surface-tension-driven flows are characterized by very high flow velocities near the interface.
When the flow is laden with finite-size particles which easily follow the fluid motion in the bulk these
are transported to the close vicinity of the interface owing to the interfacial streamline crowding. Due
to the high velocity and shear the particles can no longer perfectly follow the fluid motion near the
free surface and the interaction of the particle with the interface becomes important.
Considering the system of a thermocapillary liquid bridge1 it is shown that a simple particle—
free-surface interaction model2 can lead to a de-mixing of initially randomly distributed spherical
particles into so-called Particle Accumulation Structures (PAS)3. We show that the topology of the
flow in form of chaotic and regular streamlines (figure 1) is of crucial importance for the de-mixing
process. The model can explain the extremely rapid formation of PAS as observed in experiments4.
1 Kuhlmann, H. C. (1999): Thermocapillary convection in models of crystal growth. Springer, Heidelberg.
2 Hofmann, E., Kuhlmann, H. C. (2011): Particle accumulation on periodic orbits by repeated free surface collisions. Phys.
Fluids 23, 0721106.
3 Schwabe, D., Hintz, P., Frank, S. (1996): New features of thermocapillary convection in floating zones revealed by tracer
particle accumulation structures (PAS). Microgravity Sci. Technol. 9, 163–168.
4 Schwabe, D., Mizev, A. I., Udhayasankar, M., Tanaka, S. (2007): Formation of dynamic particle accumulation structures in
oscillatory thermocapillary flow in liquid bridges. Phys. Fluids 19, 072102.
Fig. 1: KAM tori in the surface-tension driven flow in a liquid bridge.
63
Arching structures in granular sedimentary deposits
Lukas Kulaviak1, Jindrich Hladil
2, Marek Ruzicka
1
1 Department of Multiphase Reactors (ICPF, ASCR), Prague, Czech Republic, [email protected], [email protected]
2 Geological Institute (GLI, ASCR), Prague, Czech Republic, [email protected]
Experimental results on arching structures formed in sedimentary deposits are presented.
Polydisperse mixtures of non-spherical rough natural calcite particles (ground limestone) settled
collectively in a liquid (water) and formed the deposit beneath. The morphology of the deposit layer
was studied with help of visualization and image analysis. Families of interconnected arching patterns
in form of voids or cavities were identified, of highly complex geometry1,2
. Such geometry is
quantified by measuring of total voidage and qualified by measuring of void fraction in sedimentary
vessel height. The ratio of total voidage and maximal void fraction determine degree of cavity
accumulation. The effect of the mixture composition (fraction size, volume fraction) and effect of the
liquid viscosity on the deposit structure was investigated. Simultaneously was visualised grain size
distribution and fraction size localisation. For instance, it was found, that cavities tend to form under
specific conditions, and that the large and small grains promote the void formation while the medium
grains inhibit the voiding.
1Bathurst, R.G.C. (1982): Genesis of stromatactis cavities between submarine crusts in Palaeozoic carbonate mud buildups.
Journal of the Geological Society, London 139, 165–181. 2Hladil, J. (2005): The formation of stromatactis-type fenestral structures during the sedimentation of experimental slurries –
a possible clue to a 120-year-old puzzle about stromatactis. Bulletin of Geosciences 80, 193–211.
64
Ethane 1,2-di-amineborane as a new derivative of ammonia borane for
hydrogen storage: desorption and relaxational properties
Fabrice Leardini1, A. Paolone
2, O. Palumbo
2, R. Cantelli
1, M.J. Valero-Pedraza
3, E. Perez-Mayoral
4,
M.A. Bañares3
1 Dipartimento di Fisica, Sapienza Università di Roma, Roma (Italy), [email protected]
2CNR-ISC, Piazzale A. Moro 5, 00185 Roma (Italy) 3CSIC-Instituto de Catalisis, Catalytic Spectroscopy Laboratory, Madrid (Spain)
4Dpto. de Quimica Inorganica y Quimica Tecnica, Facultad de Ciencias, UNED, Madrid (Spain)
Ethane 1,2-di-amineborane (BH3NH2CH2CH2NH2BH3) (EDAB hereafter) has been recently
considered as an interesting material for hydrogen storage applications [1]. This compound releases
ca. 10 wt% of pure hydrogen in a two step process taking place at moderate temperatures.
Here, we present novel results on the dehydrogenation properties of EDAB by means of
combined thermogravimetry (TG), differential thermal analysis (DTA) and mass spectrometry (MS)
measurements both under vacuum and under an inert gas flow. These measurements show a clear
influence of the surrounding atmosphere (vacuum or inert gas) on the decomposition pathway of
EDAB. In addition, we analyze the internal relaxation processes of EDAB by means of Anelastic
Spectroscopy measurements. An elastic energy loss peak has been observed at about 220 K, which is
related to a relaxation process in the bulk of EDAB. These results will be discussed and compared
with those previously obtained with its parent compound ammonia borane [2].
1 D. Neiner, A. Karkamkar, M. Bowden, Y.J. Choi, A. Luedtke, J. Holladay, A. Fisher, N. Szymczak and T. Autrey (2011):
Energy and Environmental Science 4, 4187-4193 2 A. Paolone, O. Palumbo, P. Rispoli, R. Cantelli and T. Autrey, J. Phys. Chem. C (2009): 113, 5872-5878
65
Drainage dynamics of water/surfactant droplets in paraffin oil
Adil Lekhlifi1, Jalil Ouazzani
2, Mickaël Antoni
3
1 UMR/CNRS 7246 MADIREL - Aix – Marseille Université 13397 – Marseille Cedex 20, [email protected]
2ARCOFLUID Parc Innolin - 33700 – Merignac
This work reports on numerical simulations of the unsteady hydrodynamics in a system
consisting of a single water droplet in a continuous paraffin oil phase. The considered droplets have
varying radius and are confined in a 1cm × 1cm square simulation domain. The model is two-
dimensional, droplets are submitted to gravity and capillary effects are accounted for1. Such systems
are typical examples of two phases, unsteady, free interface problems. The Navier-Stokes equation for
incompressible fluids is solved with the PHOENICS Software and a volume of fluids (VOF)
technique without interface reconstruction is used.
From the numerical point of view, as a droplet moves in a continuous medium, its interface
‘disappears’ upstream and is ‘created’ downstream. This simple propagation problem is still open and
raises important numerical precision and stability difficulties. When including capillary effects, the
Navier-Stokes equation is modified by a coupling term that includes the water-paraffin oil interface
curvature and surface tension2. The structure of the velocity field is shown to depend on the droplet
radius, average velocity, initial position and on the working temperature.
The effect of a soluble surfactant is also investigated3. Initially its concentration is assumed to
be uniform and small enough for the surfactant to be located only on the water-paraffin oil interface.
Due to the droplets motion, this distribution evolves with time. Surfactant is first transported towards
the apex of the droplets and, as it is assumed to be water soluble, it is then transported inside the
droplets as illustrated in the figure below. The main effect of this time evolution is a slowing down of
the overall drainage velocity.
Besides single droplet dynamics, this work also aims to propose a numerical description of
flocculation and coalescence phenomena. It is conducted within the framework of the
ISS/FSL/FASES project and, from this point of view, can be seen as a step in the direction of
numerical studies devoted to the simulation of emulsions.
1Lekhlifi, A., Antoni, M. and Ouazzani, J., Colloids and Surfaces A, (2010), 365, 70-78 2Brackbill, J. U., Kothe, D. B. and Zemach. C, J., Comput. Phys., (1992), 100, 335-353. 3Muradoglu, M., Tryggvason, G., J. Comp. Phys., (2008), 227, 2238-2262
66
Preparation and characterization of electrophoretic Fe-TiO2 films
Ineta Liepina, Gunars Bajars, Jevgenijs Gabrusenoks, Andrejs Lusis, Evalds Pentjuss
Institute of Solid State Physics, University of Latvia, Riga, Latvia, [email protected]
TiO2, both in the form of powdered material or thin film, has been increasingly used as
photocatalyst in diverse environmental applications and solar cell manufacture due to its unique
physico-chemical properties. The use of TiO2 thin films for heterogeneous photocatalysis significantly
reduces several drawbacks of practical application, such as the need of powder separation or
agglomeration of the particles. Traditionally, the photoactive coatings on flat substrates are deposited
by sol-gel, spin coating, chemical vapor deposition, sputtering or electron beam evaporation. For
coating of irregular conductive surfaces the electrochemical methods are most eligible. The
advantages of electrophoresis over other coating methods are the homogenity of deposition for
complex shapes, reduction of material usage, low contamination level and high production rates.
However, the use of TiO2 as photocatalyst also is limited because of its large band (~ 3.2 eV).
Therefore, it is necessary to prepare modified TiO2 films to improve its photoactivity under visible
light irradiation. Transition metal ion Fe3+
has been considered as an appropriate option because its
radius is similar to that of Ti4+
hence Fe3+
ions might easily incorporate into crystal lattice of TiO2 and
act as electron/hole traps.
The purpose of current work is the optimization of parameters for the sol-electrophoretic
deposition process to produce nanostructured Fe-TiO2 thin films. Obtained films were characterized
by phase composition, morphology and their microstructures using X-ray diffraction and
fluorescence, Raman spectroscopy, as well as scanning electron microscopy (SEM). The open-circuit
voltage and photocurrent density of Fe-TiO2 films were measured in order to obtain the influence of
Fe3+
doping content on the photoactivity of Fe-TiO2 films.
The results show that Fe3+
ions have been successfully doped into TiO2 crystal lattice by
substituting Ti4+
, thus inducing absorption shift toward visible region compared with the un-doped
TiO2 films. The highest photoactivity under visible light is demonstrated by 0.5-1.0 % Fe-TiO2 films.
67
Effects of carbonaceous nanoparticle on the surface properties of model
lung surfactant layers.
Libero Liggieri, Eduardo Guzman, Eva Santini, Michele Ferrari, Francesca Ravera
CNR- stituto per l’Energetica e le nterfasi, enova, taly, [email protected]
The potential toxicity and the health hazard associated with the exposition to engineered
nanoparticles and to nanoparticulate produced by the anthropic activities is a controversial subject,
limiting the use of nanotechnologies in sensitive fields, such as nanomedicine or food technologies,
and the assessment of the impact of specific productions, such as mining or energy from combustion.
Investigating the basic physico-chemical interactions of NPs with cell tissues and body fluids is
an important step to rationalize the results from classical toxicological in vitro or in vivo assays,
develop new screening methods, or design biocompatible NPs for biomedical applications .
Among the various body entry points, lungs represent probably the most important for NPs
dispersed in the environment. The physicochemical aspects of the interaction of NPs with the
pulmonary surfactant (PS) layer, composed by a mixture of lipids and some specific proteins, can be
effectively studied by a surface science approach 1, 2
.
Here we report the results of the investigation on the interaction of carbonaceous nanoparticles
with monolayers of 1,2-Dipalmitoyl-sn-glycerol-3-phosphocholine (DPPC, the main component of
PS), performed by means of a Langmuir trough equipped with a Wilhelmy plate tensiometer. The
study has pointed out that the modifications induced by these NPs to both the equilibrium and
rheological features of the lipid layer are essentially driven by the hydrophobic interactions between
particles and lipid molecules which, combined with the change of the free surface area available per
DPPC molecule, affect the packing and the molecular cohesion in the monolayer.
To better understand the potential toxicological effects, specific tests have been performed to
asses the changes induced in the functional features of the monolayer, such as the Surface Pressure –
Area isotherms, the collapse pressure, the dilational elasticity, the linearity of the surface pressure
response. The functionality during simulated respiratory cycles has also been quantified, by the help
of classical (normalized Hysteresis Area - HA, Stability Index - SI) or newly defined (Total Harmonic
Distorsion – THD) cumulative indexes.
The study shows that already a relatively simple approach, based only on tensiometric
measurements, can produce a number of useful information about the NP interaction with lung
surfactants.
Some of these results can be extended to biological membranes, DPPC also being their major
component. The application of other techniques, such as Brewster Angle Microscopy, Ellipsometry,
AFM amplifies enormously the possibility of investigating in more details the features of these lipid-
NP monolayers.
Acknowledgements: IIT-Italian Institute of Technology, Project Seed2009 “N PS-Nanoparticle
mpact on Pulmonary Surfactant nterfacial Properties”
1
Guzmán, E.; Liggieri, L.; Santini, E.; Ferrari, M.; Ravera, F.(2011): Effect of Hydrophilic and Hydrophobic Nanoparticles
on the Surface Pressure Response of DPPC Monolayers. J. Phys. Chem. C 115, 21715–21722.
2 Guzmán, E.; Liggieri, L.; Santini, E.; Ferrari, M.; Ravera, F (2012): Influence of silica nanoparticles on dilational rheology
of DPPC–palmitic acid Langmuir monolayers. Soft Matter 8, 3938-3948.
68
Changes in the morphology of emulsion droplets stabilized by surfactant
modified particles
Stéphanie Limage1, Jürgen Krägel
2, Murielle Schmitt
1, Mickaël Antoni
1, Reinhard Miller
2
1 Aix-Marseille Université – Université Paul Cézanne, Marseille, France, [email protected]
2 Max Planck Institute of Colloids and Interfaces, Potsdam-Golm, Germany, [email protected]
By optical tomographic technique it has been determined that under certain surfactant/silica
particle mixing ratios, instead of spherical oil droplets, the dispersed oil droplets in the aqueous
solution have a polymorphous shape1. The transition range from spherical to polymorphous droplet
shapes has been confirmed by bulk rheological measurements2 and scanning electron microscopy
3.
In the present contribution a systematic study on different mixed systems of silica particle-
CTAB//paraffin oil-Span 80 has been performed using optical tomographic microscopy, Cryo-SEM
and interfacial shear rheology. It has been obtained that the presence of an oil soluble surfactant has a
strong influence on the emulsion’s properties. At a certain threshold concentration of Span 80 in the
oil phase the spherical shape of dispersed oil droplets are recovered. These findings have been
confirmed by step changes in interfacial shear rheological properties and are discussed in more detail.
1 Schmitt-Rozières, M., Krägel, J., Grigoriev, D. O., Liggieri, L., Miller, R., Vincent-Bonnieu, S., Antoni, M., (2009): From
Spherical to Polymorphous Dispersed Phase Transition in Water/Oil Emulsions. Langmuir 25, 4266–4270.
2 Limage, S., Krägel, J., Schmitt, M., Dominicci, C., Miller, R., Antoni. M., (2010): Rheology and structure formation in
diluted mixed particle-surfactant systems. Langmuir 26, 16754-16761.
3 Limage, S., Schmitt, M., Dominicci, C., Vincent-Bonnieu, S., Antoni. M., (2010): Characterization of solid-stabilized
water/oil emulsions by scanning electron microscopy. Colloids and Surfaces A: Physicochem. Eng. Aspects 365, 154–161.
69
Effect of gravity on heat and mass transfer phenomena during the
immersion of a water saturated porous matrix in hot oil.
John S. Lioumbas1, Thodoris D. Karapantsios
1
1 Division of Chemical Technology, Department of Chemistry,
Aristotle University of Thessaloniki, Thessaloniki, Univ. Box 116, 54124, Greece
The effective enhancement in boiling heat transfer provided by porous-layer coatings is mainly
attributed to combinations of an extended surface area effect, an increased nucleation site density
effect and the bubble dynamics at the top of the layer adjacent to the liquid pool. However, up to now,
no model has been proposed putting forward the above concepts in order to describe the heat transfer
coefficient on such porous surfaces.
In order to provide original experimental evidence to support such modeling efforts, an
experiment is conceived, where a ceramic porous medium saturated with water is submerged in a hot
immiscible liquid (i.e. oil) having only its top surface exposed to the oil. The hot liquid triggers
boiling over and right below the surface of the porous medium. The employed heating approach
cancels the effect of natural convection in the surrounding liquid layers since the hot oil is above the
cold porous matrix and circumvents the problem of non-uniform heating of the exposed porous
surface which is a significant source of unsteadiness when heating porous substrates by electrical or
radiation means from their bottom. As a result, the employed heating approach leads to smoother
boiling operation.
Increased levels of gravity in the range from 1g to 9g are used as a tool (experiments
conducted in the Large Diameter Centrifuge at ESA/ESTEC) to modify bubble dynamics over the
porous surface. Experiments are conducted at a constant oil temperature (150oC). Continuous
temperature measurements inside the oil and inside the porous matrix (at 0.5, 1.0 and 1.5mm below
the surface), in conjunction with high speed imaging of emerging vapour bubbles over the porous
surface (i.e. bubble growth rate, bubble detachment diameter, bubble detachment mode, bubble
departure velocity, bubble population density), reveal the effect of gravity level on boiling phenomena
over the porous matrix. The analysis of these measurements indicates a strongly non-linear effect of
increasing gravity on boiling phenomena over porous media which is not predicted by any existing
model or correlation.
70
Effect of thermal gradients on heat and mass transfer phenomena
during the immersion of a water saturated porous matrix in hot oil.
John S. Lioumbas1, Nikolaos Lestos
2, Thodoris D. Karapantsios
1
1 Division of Chemical Technology, Department of Chemistry,
Aristotle University of Thessaloniki, Thessaloniki, Univ. Box 116, 54124, Greece 2 Hephaestus Boiler Makers & Engineering S.A., Thessaloniki, Greece
Protecting surfaces from high heat fluxes by using porous materials saturated with liquid water
is an innovative new way designed to shield a substance from absorbing excessive heat from an
outside source. The use of liquid instead of gas as a coolant has the advantage that the heat of
vaporization can be used as an additional cooling mechanism
The interplay between the boiling mechanisms over and just below the surface of a porous
matrix and the bubbles behavior above it is experimentally studied during the immersion of a ceramic
porous medium saturated with water inside a bath of a hot immiscible liquid (i.e. oil with temperature
well above the water boiling point). To simplify the geometry of the problem, the porous medium has
only one surface exposed to hot oil, the others being thermally insulated. Therefore, the hot oil
triggers boiling solely over the exposed porous surface. The employed unconventional top-down
heating approach by hot oil offers two distinct advantages compared to conventional approaches of
heating porous substrates by electrical or radiation means from their bottom. These are:
• Suppression of the effect of natural convection in the surrounding liquid layers since the hot
oil is above the cold porous medium.
• More uniform heating of the exposed porous surface (which is a significant source of
unsteadiness with conventional heating methods) leading to smoother boiling operation.
Continuous temperature measurements inside the oil bath, on the oil-porous interface and inside
the porous matrix (i.e. 0.5, 1.0 and 1.5mm below the surface) are acquired along with optical images
of bubbles activity (based on fast-video recordings) over the exposed porous surface. These are cross-
examined aiming at identifying a possible relation between bubbles behavior and boiling heat transfer
inside the porous matrix. The influence of the oil bath’s temperature, Toil, on the above phenomena is
studied by testing various Toil values (i.e. 150, 160, 170 and 180oC).
71
Controlling the evaporation of sessile drops by surface softness
Marcus C. Lopes & Elmar Bonaccurso
Technische Universität Darmstadt, Experimental Interface Physics Group, Center of Smart Interfaces, Petersenstr.
17, 64287 Darmstadt, Germany
E-mail: [email protected]
We demonstrate how the deformation of the substrate close to the triple-phase contact line
influences the evaporation process of a sessile drop by using surfaces with similar wettability, but
different mechanical properties. We show that water drops on soft surfaces (Young’s modulus ~0.02
MPa) evaporate faster than on hard surfaces (Young’s modulus ~1.5 MPa). The faster evaporation
rates on soft surfaces can be related to a different dynamic evolution of the receding contact angle,
which is a direct consequence of the substrate deformation close to the triple-phase contact line. By
adjusting the substrate softness we are able to control the transition between constant contact radius
and constant contact angle evaporation modes.
Figure 1: Volume change of a sessile water drop during evaporation. The symbols represent the
experimental data on different soft polydimethylsiloxane (PDMS) surfaces. The solid and dashed lines
represent the expected volume change in CCA and CCR mode respectively.
Reference
Lopes M.C., Bonaccurso E., Evaporation control of sessile water drops by soft viscoelastic surfaces, Soft Matter 8,
7875 (2012)
0 100 200 3001E-4
1E-3
0.01
0.1
1
E=1.5MPa (PDMS 10:1)
E=0.2MPa (PDMS 20:1)
Dro
p V
olu
me (
µl)
Time (s)
E=0.06MPa (PDMS 30:1)
E=0.02MPa (PDMS 50:1)
CCR Theory
CCA Theory
72
How to choose among different kinds of superhydrophobic surfaces?
Innovative test protocol on ageing of superhydrophobic surfaces
I. Malavasi1, I. Bernagozzi
1, C. Antonini
1, +, M. Marengo
1
1 Department of Engineering, University of Bergamo, Viale Marconi 5, 24044 Dalmine, Italy, [email protected]
+ Current address: Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering
Department, ETH Zürich, Switzerland.
In this paper we present the development and the set-up of a laboratory durability test protocol
to compare resistance and aging of superhydropobic surfaces. Herein a new protocol is proposed to
evaluate resistance of superhydrophobic surfaces (SHSs), with special attention to the feasibility. It is
structured to be carried out in a common laboratory research, using easily available reagents and low-
cost materials.
The protocol consists of nine different tests to simulate surface exposure to potentially harmful
different environments. Tests include immersions in water and organic solvents, immersion in
solutions of acid, alkali and salt, exposure to erosion, heating and UV rays. Different tests conditions
and results are discussed in the paper. Superhydrophobic features of the surfaces are measured
evaluating the advancing contact angle and the contact angle hysteresis with the method of the sessile
drop: measures are performed before and after each test, in order to evaluate qualitatively and
quantitatively the differences in superhydrophobicity.
The proposed protocol allows evaluating not only the resistance of a surface to damaging such
as immersion in acid or UV irradiation, but also which is the most suitable use for a surface,
considering its durability. In addition, the data analysis from the protocol can be used to provide an
indication on how the procedure used for the surface realization allows achieving homogeneous
surfaces.
73
Wedge filling: A novel way to observe critical surface phenomena
Alexandr Malijevský1, Andrew O. Parry
2
1 E. Hála Laboratory of Thermodynamics, Institute of Chemical Process Fundamentals, Academy of Sciences, 16502 Prague
6, Czech Republic [email protected] 2 Department of Mathematics, Imperial College London, London SW7 2B7, UK [email protected]
We present results of a microscopic density functional theory study of wedge filling transitions,
at a right-angle wedge, in the presence of dispersion-like wall-fluid forces. Far from the corner the
walls of the wedge show a first-order wetting transition at a temperature wT which is progressively
closer to the bulk critical temperature cT as the strength of the wall forces is reduced. In addition, the
meniscus formed near the corner undergoes a filling transition at a temperature wf TT the value of
which is found to be in excellent agreement with macroscopic predictions. We show that the filling
transition is first-order if it occurs far from the critical point but is continuous if fT is close to cT
even though the walls still show first-order wetting behaviour. For this continuous transition the
distance of the meniscus from the apex grows as wTT fw
with critical exponent 46.0w
in good agreement with phenomenological effective Hamiltonian predictions. Our results suggest that
critical filling transitions, with accompanying large scale universal interfacial fluctuation effects, are
more generic than thought previously, and are experimentally accessible.
74
Co-adsorption in mixed protein and/or surfactant solutions studied by
solution exchange experiments with pendant bubbles and thin films
Krastanka G. Marinova, Elka Basheva, Rumyana Stanimirova, Mihail T. Georgiev, Nikola
Alexandrov, Krassimir D. Danov, Peter A. Kralchevsky
Department of Chemical Engineering, St. Kl. Ohridski University of Sofia, Sofia, Bulgaria, [email protected]
Set of complementary experimental methods is used to determine the properties of adsorption
layers of solutions containing two proteins or a protein and surfactant and to qualitatively analyze the
effect of the individual components: Phase exchange experiments with (i) rising bubbles to determine
the surface tension by the DSA method, combined with surface dilatational rheology measurements;
and (ii) thin films observations for determining the film thickness and stability.
The properties of the mixed adsorption layers and thin films have been compared in two
different cases: (i) Parallel adsorption from mixed solutions of the two components; (ii) Sequential
adsorption realized by exchange of the solution around the bubble or in the films.
The applied combination of experimental methods and data interpretation give the opportunity
to analyze in details the role of individual components for the overall behavior and stability of the
mixed system,1 and could be further applied to other protein + surfactant blends.
1 K.G. Marinova, R.D. Stanimirova, M.T. Georgiev, N.A. Alexandrov, E.S. Basheva, P.A. Kralchevsky, in
Colloid and Interface Chemistry for Nanotechnology, Taylor & Francis, Boca Raton, FL, 2013.; Chapter 18.
75
Protein/surface interactions: the role of nanoparticle chemical
composition and size on the fibrinogen adsorption
Arianna Marucco1, Ivana Fenoglio
1, Francesco Turci
1 and Bice Fubini
1
1 Department of Chemistry, niversity of Torino, nterdepartmental Centre “ . Scansetti” for Studies on Asbestos and Other
Toxic Particulates and Interdepartmental Center for Nanostructured Interfaces and Surfaces, Torino, Italy,
The proteins/surface interaction is considered the first event that occurs when an inorganic
surface comes in contact with a biological fluids. This interaction is influenced by a series of
physico-chemical factors related to the features of the inorganic surface
(hydrophobicity/hydrophilicity, charge, nanotopography, curvature, reactivity, chirality), medium (pH
and ionic strength) and protein characteristics (charge and resistance to structural deformation) [1-6].
The nanometric silica particles (SiO2) and carbon are widely used in industrial applications for
example as excipients in pharmaceuticals, cosmetics and as additives in plastics, rubber. These
materials are also studied for applications in nanomedicine as possible carriers for diagnostic and
therapeutic use [7]. Exposure to these materials, both accidental and intentional, can have harmful
effects on human health. The nano particles, once penetrate into the body, may across biological
barriers and enter the bloodstream. This is the cause of the increase in cardiovascular diseases upon
peaks of nanosize particulate matter. Fibrinogen was selected among other plasma proteins because of
its relevance to blood clotting processes and in the recruitment of macrophage and
leukocyte.Conformational changes mediated by the surface of implantable medical devices are known
to activate fibrinogen, leading to the exposure to receptors embedded in the native protein [8].
This study aims to elucidate the adsorption behavior of fibrinogen on substrates showing
different chemical surface population (silanols and siloxane in the case of silica while carboxylic and
alcoholic groups on carbon nanoparticles).The extent of the protein coverage and the irreversibility of
the adsorption process were monitored by combining curves of protein adsorption and shift of ζ
potential respectively. The evaluation of protein conformational change of fibrinogen tertiary
structure was evidenced by Raman spectroscopy.
1Lundqvist, M., Sethson, I., Jonsson, B.H., (2004): Protein adsorption onto silica nanoparticles: Conformational changes
depend on the particles' curvature and the protein stability. Langmuir, 20, 10639-10647.
2Lundqvist, M., Stigler, J., Elia,G., Lynch, I., Cedervall, T., and Dawson, K. A., (2008): Nanoparticles size and surface
properties determine the protein corona with possible implications for biological impacts, Pnas, 105 (38), 14265-14270.
3Roach, P., Farrar, D., Perry, C.C., (2006): Surface tailoring for controlled protein adsorption: Effect of topography at the
nanometer scale and chemistry, Journal of the American Chemical Society, 128, 3939-3945.
4Nel, A., Madler, L., Velegol, D., Xia, T., Hoek, E., Somasundaran, P., Klaessig, F., Castranova, V., Thompson, M., (2009):
Understanding biophysicochemical interactions at the nano-bio interface, Nature Materials, 8 (7), 543-57.
5Walczyk, D., Bombelli, F.B.,. Monopoli, M.P., Lynch, I., Dawson, K.A., (2010): What the Cell "Sees" in Bionanoscience,
Journal of the American Chemical Society, 132, 5761-5768. 6 Fenoglio, I., Fubini, B., Ghibaudi, E. M., Turci, F., (2011): Multiple aspects of the interaction of biomacromolecules with
inorganic surfaces, Advanced Drug Delivery Reviews, 63, 1186–1209
7 Prokop, A., Davidson, J.M.,(2008): Nanovehicular intracellular delivery systems, Journal of pharmaceutical sciences, 97,
3518-3590
8Thevenot, P., Hu, W., and Tang, L., (2008): Surface chemistry influences implant biocompatibility. Current Topics in
medicinal chemistry, 8, 270-280
76
Dielectrowetting Control of Droplets of Non-Conducting Liquids
Glen McHale1, Christophe Trabi
1, Carl V. Brown
2, Michael I. Newton
2, Naresh Sampara
2
1 Faculty of Engineering & Environment, Northumbria University, Newcastle upon Tyne, UK
[email protected] 2 School of Science & Technology, Nottingham Trent University, UK
The contact angle of a droplet of a conducting liquid on a substrate can be controlled using a
voltage by making the droplet part of a capacitive structure where the droplet contact area forms one
electrode to create an electrowetting-on-dielectric (EWOD) configuration1. This principle has been
used to create liquid optical devices and as a method of creating droplet microfluidic systems.
However, the substrate must include an electrode coated with a thin, and typically hydrophobic, solid
insulating layer and the liquid must be conducting, typically a salt solution, and have a direct
electrical contact. In this work we show that reversible voltage programmed control of droplet wetting
of a surface can be achieved using non-conducting dielectric liquids and without direct electrical
contact.2 Our approach uses non-uniform electric fields and liquid dielectrophoresis to alter the energy
balance of a droplet on a solid surface. We show experimentally and theoretically that for thick
droplets the change in the cosine of the contact angle is proportional to the square of the applied
voltage and obeys a similar equation to that found for EWOD. In this limit, the important surface free
energy changes occur by displacements of the contact line. We also show that as the droplet spreads
and becomes thinner, changes in surface free energy can occur by a wrinkling/undulation forming in
the liquid-vapor interface3-5
. We discuss how these effects could be used to create droplet microfluidic
systems without the need for direct electrical contact and without the restriction to conducting liquids.
1 Mugele, F., Baret, J.-C. (2005): Electrowetting: from basics to applications. J. Phys: Condens. Matt. 17, R705–R774.
2 McHale, G., Brown, C.V., Newton, M.I., Wells, G.G., Sampara, N. (2011): Dielectrowetting driven spreading of droplets.
Phys. Rev. Lett. 107, art. 186101.
3 Brown, C.V., McHale, G., Mottram, N.J. (2011): Analysis of a static wrinkle on the surface of a thin dielectric liquid layer
formed by dielectrophoresis forces. J. Appl. Phys. 110, art. 024107.
4 Brown, C. V., Al-Shabib, W., Wells, G. G., McHale, G., Newton, M. I. (2010): Amplitude scaling of a static wrinkle at an
oil-air interface created by dielectrophoresis forces. Appl. Phys. Lett. 97, art. 242904.
5 Brown, C. V., Wells, G. G., Newton, M. I., McHale, G. (2009): Voltage-programmable liquid optical interface. Nature
Photonics 3, 403-405.
Acknowledgement: We acknowledge funding from the UK EPSRC (EP/E063489/1). NS acknowledges funding from
Nottingham Trent University.
77
Capillary Rise and Imbibition in Tubes and Channels
Glen McHale1, Christophe Trabi
1, Michael I. Newton
2, Fouzia O. Ouali
2,
Haadi Javed2, Neil J. Shirtcliffe
3
1 Faculty of Engineering & Environment, Northumbria University, Newcastle upon Tyne, UK
[email protected] 2 School of Science & Technology, Nottingham Trent University, Nottingham, UK
3Faculty of Technology & Bionics, Rhine-Waal University of Applied Sciences, Kleve, Germany
When a vertically mounted circular cross-section tube is brought into contact with a wetting
liquid the liquid penetrates and rises under the action of capillary forces at a rate determined by
viscous forces until it reaches an equilibrium height. The same physical principles apply as the tube is
tilted towards the horizontal, but gravity becomes ever less influential. If the tube is replaced by a
rectangular cross-section closed or open channel (i.e. with or without a top enclosing surface) then
many of the same principles apply. However, the existence of 90 degree corners between the sides
and the bottom/top of the channels leads to a corner filling capillary problem1. In this work we report
experiments on capillary rise of polydimethylsiloxane oils into vertically mounted circular and square
cross-section (closed) tubes and open-rectangular channels. We fit the data to both the exact
differential equation describing this situation and to an analytical visco-gravitational solution valid for
vertically oriented tubes. We report that for square tubes and rectangular channels liquid filaments run
along the corners in advance of the main body of liquid, as predicted from corner-filling
considerations2. We investigate the effect of tilting circular cross-section tubes towards the horizontal.
We compare fitting data to the exact differential equation, to the visco-gravitational solution and to
the Bousanquet solution, which is valid for horizontal tubes. We find that the edge running filaments
can be observed for horizontally mounted square cross-section tubes and open-rectangular channels.
We discuss the implications of these observations for microfluidics.
1 Ponomarenko, A., Quéré, D., Clanet, C. (2011): A universal law for capillary rise in corners. J. Fluid Mech. 666, 146-154.
2 Ouali, F.F., McHale, G., Javed, H., Trabi, C., Shirtcliffe, N.J., Newton, M.I. (2012): Wetting considerations in capillary
rise and imbibition in closed square tubes and open rectangular cross-section channels, submitted to Microfluid. Nanofluid.
Acknowledgement: We acknowledge funding from the K EPSRC (EP/E063489/1). One of the authors’ (HJ)
acknowledges Nottingham Trent University for providing a PhD studentship.
78
Building the Pyramids: Perfect Bubble Crystals
Aaron Meagher, David McAteer, Stefan Hutzler, Denis Weaire, David Whyte
School of Physics, Trinity College Dublin, Dublin 2, Ireland, [email protected]
The use of appropriate flat-sided pyramidal containers to grow ordered foams allows single
crystals to be formed1. In the case of face centred cubic crystals these have been prepared with up to
500 bubbles. Strained and deliberately defective crystals can also be grown. The growth of simple
cubic and body centred cubic crystals is limited by instability: preliminary results are presented for
these, as well as ordered bidisperse foams. In addition, a method of quantifying the structure of such
crystals is described.
1 Meagher, A. J., McAteer, D., Hutzler, S. and Weaire, D. (2013): Building the Pyramids: Perfect Bubble Crystals. Phil.
Mag. (submitted)
Photograph of an fcc bubble crystal produced in a 3-sided 60◦ pyramid. The samples consist of 8 layers of bubbles with
diameter 2.42±0.03 mm. The foam crystal is imaged from the base, i.e. in a ⟨ 111 ⟩ direction.
(Pyramid fabricated with an Object 300 rapid prototype machine using Object Vero Clear polymer. )
Acknowledgements: Research supported by Science Foundation Ireland (08/RFP/MTR1083), the European Space Agency
(MAP AO-99-108:C14914/02/NL/SH and AO-99-075:C14308/00/NL/SH) and European Union MPNS COST Action
MP1106. Special thanks to Professor Martin Hegner and Jason Jensen (TCD) for help in the fabrication of these pyramids
and use of their Object 300 3D printer.
79
Tailoring carbon materials for specific applications
J. Angel Menéndez, A. Arenillas
Instituto Nacional del Carbón, CSIC, Apartado 73, 33080 Oviedo, Spain
[email protected] & [email protected]
Carbon Xerogels are a polymeric material that allows tailoring its physical properties (i.e.
nanoporosity), chemical properties and even the final form of the material according to the
requirements of the application they have been design for. This is due to the significant influence of
the synthesis conditions on the polymerisation process of the precursors used. Thus, it is possible to
control the meso/macroporosity independently of the microporosity and specific surface area,
allowing different combinations of macro/meso/microporosity totally adapted to the necessities of the
application.
The base materials are pure carbons (>95 wt% C) but it is possible to increase the presence of
other heteroatoms (i.e. Oxygen, Nitrogen, or even metals) including them during the polymerisation
step or throughout post-synthesis treatments. It is also possible to incorporate easily other
nanoparticles (i.e., nanotubes, nanofibers) to enhance certain properties for the final utilisation.
An additional advantage of these materials is that they can be obtained in different forms as
monoliths, specific shapes, powder, spheres, films, etc. without the need of binders or sophisticated
processes.
Taking all of these into account, the possible applications of these materials are enormous, with
significant results in electrochemistry and electrocatalysis, in hydrogen storage, adsorption, gas
separation, catalysts support, etc.
The synthesis of these materials are optimized and developed at the laboratory scale by our
research group MCAT (www.incar.csic.es/mcat) , but bigger production is also possible throughout
our spin-off XEROLUTIONS (www.xerolutions.com) with a patented process.
80
Bubbles in humans: etiology, detection, symptoms –
The role of Hyperbaric Medicine
Thodoris Mesimeris
1 St Paul G. Hospital, Thessaloniki, Greece, [email protected]
Industrial revolution through the invention of reliable long-lasting air pumps (compressors and
vacuum pumps) has modified the working ability at ambient pressures higher and lower than normal
atmospheric pressure (1 ATA): -HYPERBARIC (subsea, underground tunneling, hyperbaric
facilities) - HYPOBARIC (aeronautical, space activities).
At sea level (one atmosphere or 14,7 pounds per square inch), the average human body contains
about one liter of nitrogen (air: 21% oxygen, 79% nitrogen) dissolved in body tissues (chiefly in
blood). Oxygen (from breathing air) has usually low content in the body as it is largely consumed in
metabolic reactions. The carbon dioxide produced from these metabolic reactions (plus excess
oxygen) is rapidly adjusted to pressure changes through breathing. On the contrary, if the partial
pressure of inhaled nitrogen (ppN2) changes according to ambient pressure, being higher or lower than
in 1 ATA (0.79 ATA), the ppN2 dissolved in the body will attain a matching level and some quantities
of N2 will be absorbed or desorbed from the human body until N2 tensions in the inhaled air (lungs)
and in the tissues (biological interfaces) will be again in balance.
If the ambient pressure (in hyperbaric or hypobaric exposure) decreases faster than the body
can off-load the excess of nitrogen, the critical super saturation point may be exceeded, and the
dissolved gas may come out of solution in the form of bubbles because decreasing pressure lowers the
solubility of gas in liquid. The clinical syndrome of bubbles over all biological interfaces is known as
Decompression Sickness (DCS). The type and severity of DCS is determined by the concentration
(volume) and size of bubbles along with the site in the human body where they appear.
Bubbles formed in the body can create mechanical effects (impinging on nerve endings and
thus causing pain, tissue tearing) or blood-bubble interfacial effects. As far as interfacial effects are
concerned, bubbles appear as foreign bodies in the organism and initiate a defense mechanism. This
defense mechanism triggers a cascade of reactions: vasoconstriction, leakage of liquids from the
intravascular to extravascular spaces, platelets aggregation causing ischemia, blood viscosity increase
and blood flow decrease. Clinical outcome of severe cases may be fatal.
Therapeutic approach of DCS is related to the compression of the bubbles through increased
pressure (Boyle’s law) and simultaneous inhalation of oxygen at a level higher than atmospheric
pressure. This kind of treatment is known as Hyperbaric medicine (HM), and is performed in air-tight
pressure chambers delivering 100% oxygen. Operation is performed by trained personnel who
monitor the patient and adjust the schedule as required. HM has also shown great effectiveness in
treating other illnesses due to the important increase of oxygen concentration in hypoxic human
tissues. However, HM personnel is exposed to the risk of DCS under off nominal operation the
chamber, e.g. accident, system failure, urgent run away.
Prevention of DCS through detection of bubbles presence is considered of high significance for
the safety of involved humans in all related activities. Ultrasonic Doppler devices are customary
employed to detect bubbles, emitting ultrasounds which are reflected off moving bubbles.
Unfortunately, signal evaluation is largely subjective and identified scale indexes do not correspond to
clinical status of DCS. Current research focuses on new methods (e.g. through electrical impedance)
in order to define safer diagnostic models for prevention of DCS.
81
Thermodynamic and kinetic characterization
of the catalysed LiBH4 - MgH2 system
Chiara Milanese1, Julian Jepsen
2, Alessandro Girella
1, Jose Bellosta von Colbe
2,
Martin Dornheim2, Thomas Klassen
2, Amedeo Marini
1
1 Pavia Hydrogen Lab, C.S.G.I. & University of Pavia, Chemistry Department, Pavia, Italy, [email protected]
2 Helmholtz-Zentrum Geesthacht, Department of Nanotechnology, Institute of Materials Research, Geesthacht, Germany,
The LiBH4 – MgH2 system is of particular interest among the reactive hydride composites due
to its high gravimetric capacity and the full reversibility of the sorption reactions. With the aim to
realize a hydrogen storage tank based on this material, a full physico-chemical characterization of the
2:1 molar ratio composition has been undertaken, in order to obtain data fundamental for the
simulation of the sorption processes and the design of the system. In particular, the reaction enthalpy,
entropy and activation energy for all the sorption steps have been evaluated by PCT and coupled
manometric – calorimetric measurements. Optical microscopy has been used to confirm the evolution
of the different physico-chemical processes involving liquid and gas phases.
Concerning the response of the system to the exothermal absorption and endothermal
desorption reaction, the thermal conductivity of the composite in the charged and discharged state has
been measured by the transient source method as a function of the temperature and the density,
modified by compaction, of the samples.
The effect of the density on the sorption properties and the cycling of the materials has been
explored by kinetic measurements and scanning electron microscope investigations up to 20 full
charging/discharging cycles on pellets compacted at pressure as high as 900 MPa. A strong effect has
been noticed on the number of the so-called activation cycles and on the absorption kinetic
performance, while no decrepitation and disaggregation effects have been observed, in spite of the
presence of the borohydride liquid phase.
82
In situ generation of Ag nanoparticles on polyester and cotton fabrics by
photoreduction using TiO2 nanoparticles
Milica Milošević1, Zoran Šaponjić
1, Marija Radoičić
1, Tim Nunney
2,
Darka Marković3, Jovan Nedeljković
1 and Maja Radetić
4
1Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia, [email protected]
2Thermo Fisher Scientific, The Birches Industrial Estate, East Grinstead, West Sussex, RH19 1UB, UK 3Innovation center Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia
4Textile Engineering Department, Faculty of Technology and Metallurgy, University of Belgrade, Belgrade, Serbia
This study discusses the possibility of in situ generation of Ag NPs by photoreduction of Ag+
ions from the solution, in the presence of amino acid alanine and methanol, on the surface of TiO2
NPs deposited on polyester and cotton fabrics. Surface modification of TiO2 NPs with amino acids
such as alanine resulted in the replacement of TiO2 surface hydroxyl groups and coordination of
surface Ti atoms with a carboxyl group which simultaneously bind silver ions [1-2]. Such
arrangement results in enhanced reduction properties of photogenerated electrons in TiO2. In this
system we employed methyl alcohol as an effective hole-scavenger (E°-(CH3OH/·CH2OH) = +1.2 V)
which eventually also provides an increase of the yield of the trapped electrons due to the formation
of the electron-donating species ·CH2OH (E°(
·CH2-OH/CH2O) = -0.95 V). The net effect is that from
one photon of absorbed light by TiO2 nanoparticles two electrons for reduction of Ag ions are formed.
The impregnation of polyester and cotton fibers with TiO2 and Ag nanoparticles generated in
described manner brought about certain morphological and chemical changes, which were evaluated
by SEM, XRD and XPS, respectively.
Such nanocomposite textile material provides excellent antimicrobial activity against Gram-
negative bacterium E. coli, Gram-positive bacterium S. aureus and fungus C. albicans. Maximum
microbial reduction was preserved even after ten washing cycles. In spite of satisfactory laundering
durability, the release of silver occurred during washing especially in the first three washing cycles
when the most of the deposited silver leached from the fabric. The leaching of silver was also
presented when the polyester fabrics were exposed to artificial sweat at pH 5.5 and pH 8.0 for 24 h.
In addition to excellent antimicrobial properties, TiO2/Ag nanoparticles imparted maximum UV
protection to polyester and cotton fabrics.
1 Rajh T., Ostafin A., Mićić O. ., Tiede D. M., Thurnauer M. C. (1996): Surface modification of small particle TiO2 colloids
with cysteine for enhanced photochemical reduction: An EPR study. Journal of Physical Chemistry 100, 4538-4545.
2 Rajh T., Nedeljković J., Chen L. X.,. Tiede D. M, Thurnauer M. C. (1998): Photoreduction of copper on TiO2
nanoparticles modified with polydentate ligands. J. Adv. Oxid. Technol. 3, 292-298.
83
Diagnostic studies to improve abuse tolerance and life of Li-air batteries
Mojtaba Mirzaeian1, Peter Hall
2, Anthony Rennie
2, Asoo Noofeli
2
1 School of Engineering, University of the West of Scotland, Paisley, UK, [email protected]
2 Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
Among different energy-storage technologies, lithium air batteries will play an increasingly
important role in meeting the higher requirements of upcoming systems. However, major challenges
will have to be solved if the battery is to succeed. This study was aimed to identify root-cause of these
major issues toward fixing the existing, unsatisfactory state of Li based cells and also understand their
performance under different conditions to improve the battery’s safety in practical applications where
safety and reliability of the device is crucial. The most recent example of lithium based batteries’
safety problem was witnessed when the entire fleet of 50 Boeing 787s was grounded by regulators
globally after a battery fire on board a Japan Airlines plane parked in Boston and after battery
problems and smoke in the cockpit forced an emergency landing by an All Nippon Airways 787 in
Japan.
In this work the electrochemical performance of the Li/O2 battery under different operation
conditions was studied to elucidate the effects of discharge rate, discharge depth and charge taper
voltage on the performance, state of charge and abuse tolerance of the battery. Galvanostatic
discharge profiles at various discharge rates showed that the effective capacity of the cell drops with
increase in the discharge rate. However the cell's cycleability improved with increase in the discharge
rate probably due to the ease of stripping the Li2O2 film formed on the electrode surface reversibly at
higher rates, compared with the incomplete removal of discharge products formed within the pores at
low discharge rates.
The performance of the cell discharged at different cut off voltages showed that decreasing the
depth of discharge decreases the rate of capacity fade and improves the cell cycleability. Study of the
cell performance at different charge taper voltages showed that the cell capacity increases with charge
taper voltage for charge potentials up to 4.45 V. For charge potentials above 4.45 V, the cell
performance deteriorates with increasing charge taper voltage significantly, probably due to the
decomposition of the electrolyte at higher charge potentials. It is believed that a potential of 4.45 V is
the edge of breakdown potential of propylene carbonate based electrolytes used in the battery and a
discharge potential above this will result in the overcharge abuse of the cell.
84
Challenges in Translational Nanomedicine
S. M. Moghimi
Centre for Pharmaceutical Nanotechnology and Nanotoxicology, and NanoScience Centre, University of
Copenhagen, DK-2100 Copenhagen, Denmark
Nanomedicine encompasses enabling technologies to achieve and facilitate earlier and more
precise disease diagnosis, effective targeted therapies (eliminating side effects), better therapy and
monitoring. Furthermore, the nanomedicine umbrella is considered the enabling instrument for
personalized, targeted and regenerative medicine that can deal with grand challenges of chronic
diseases in an aging population. This may enhance the quality of life, support a healthier more
independent aging population and instrumental for cost-effective health care. A long-term goal is
‘personalization’ of nanomedicine and theranostics but can nanomedicine be personalized for
prognosis, diagnosis and drug treatment? At large, and from a high risk−high gain perspective, this
requires a heroic integration of multifaceted health nanotechnology platforms with genomics and
epigenomics knowledge together with complex computational approaches and bioinformatics. But
how and where do we start? Which diseases do we focus? Which markets should we consider? What
business models should we apply? Immunological reactions to man-made nanomaterials and
nanomedicines are particularly notable. Provisions in innate immunity gene profiling for
nanomedicine risk assessment and safety may serve a good starting point, and forms the centre of this
discussion.
85
INFORMATION ON MP1103
Amelia Montone
ENEA, Materials Technology Unit, Research Centre of Casaccia, Rome, Italy, [email protected]
COST Action MP1103 “Nanostructured Materials for Solid State Hydrogen Storage” deals
with the future of energy storage and aims to set up a competitive and coordinated network capable to
define new and unexplored ways for Solid State Hydrogen Storage (SSHS) by innovative and
interdisciplinary research.
The objective is to explore in a rational way the possible feasible solutions to the problem f the
SSHS by making use of the full potential of nanostructuring techniques and nanotechnology. The
Action will develop innovative nanostructured materials creating the conditions for their adequate
implementation in stationary and transport applications to sustain in medium-long terms the
economies of European countries. One of the main aims is the establishment of a Pan-European and
multidisciplinary research and communication platform that can develop the Science & Technology
potential of SSHS thus contributing actively to the regional and European economy and social
welfare.
This COST Action was started in October 2011 and will last for four years. Nowadays about
200 researchers coming from 24 European Countries and from 4 Institutions from non-COST
Countries participate in this Action, contributing to create a critical mass of researchers in the field of
the SSHS.
Four Working Groups are active for the scientific debate and the consequent synergy:
• Synthesis of novel materials with optimized properties,
• High resolution and high sensitivity characterization of atomic level structure and
microstructural features,
• Characterization of hydrogen storage properties both at the laboratory level and at the scale
of prototype tanks,
• Computational modelling of processes relevant to SSHS.
86
Formation of nanoparticle ring-like deposits at driven receding contact
lines
Carmen L. Moraila-Martínez1, Miguel A. Cabrerizo-Vílchez
1 and Miguel A. Rodríguez-Valverde
1
1 Biocolloid and Fluid Physics Group, Applied Physics Department, Faculty of Sciences,
University of Granada, E-18071 Granada, Spain, [email protected]
In order to produce well-ordered structures via evaporation, it is essential to control the
evaporation flux, solute concentration, interaction between the solute and the substrate, etc. During
the drying of particle suspensions, the particle deposition process can be dictated by electrostatic and
van der Waals forces. However, the complex physics involved in the drying of colloidal particle
suspensions and the erratic contact line dynamics of evaporating sessile drops complicate the analysis
of the problem. In this work, we propose a new methodology based on shrinking sessile drops to
standardize the contact line dynamics of evaporating drops, but with no observable evaporation
(macroscopic scale). We used a microinjector to decrease the drop volume through a small hole
drilled in the substrate. Unlike drying drops, with our methodology the particle concentration in the
drop bulk remained constant during the entire process and the macroevaporation was negligible. We
probed the arrangement of nanoparticles at driven receding contact lines, with low capillary numbers
and at time scales shorter than during free evaporation. The electrostatic double layer interactions
were modified by diluting the nanoparticles in buffer solutions at different pH values. We also
examined the impact of the wettability contrast between the substrate and the particle on the deposit
morphology. We found that the ring-like deposits formed at driven contact lines might be suppressed
with strongly interacting particles.
1 Carmen L. Moraila-Martínez, Miguel A. Cabrerizo-Vílchez and Miguel A. Rodríguez-Valverde (2012): The role of the
electrostatic double layer interactions in the formation of nanoparticle ring-like deposits at driven receding contact lines.
Soft Matter, In press. DOI: 10.1039/c2sm27040d
87
Impact of water soluble polymers on oil removal by air flotation
M. Mouazen, M. Boufarguine, I. Hénaut, J-F. Argillier
IFP Énergies Nouvelles, 1-4 avenue de Bois Préau, 92852 Rueil-Malmaison, France
Gas flotation column is one method used in petroleum field to treat oily wastewater coming
from water flooding or enhanced oil recovery (EOR). It is well-known that smaller gas bubbles and
bigger oil droplets favor oil removal percentage from oily wastewater. This principle has been
confirmed experimentally in a Newtonian fluid: glycerol/water mixture. An increase in the viscosity
raises the bubble sizes which decreases the oil removal efficiency. In the same conditions using of
pseudoplastic continuous phase ( high polymer weight polyacrylamide solution) shows two antagonist
effects: On one hand smaller bubbles are obtained that normally favors the oil elimination, but on the
other hand an uneven spatial distribution of bubbles aligned vertically as (strings of bubbles) is
obtained that decreases the oil removal efficiency. Clearly the change of rheological behavior leads to
a different rise of bubbles. Results show a corridor with a pronounced acceleration observed in shear
thinning polymer solutions. They results in fewer contacts between bubbles and oil droplets. As a
consequence water quality gets worse.
88
Adsorption layer properties of alkyl trimethyl ammonium bromides
CnTAB at different liquid interfaces
Nenad Mucic1, Nina M. Kovalchuk
1,2, Eugene V. Aksenenko
3, Valentin B. Fainerman
4
and Reinhard Miller1
1 Max-Planck Institute of Colloids & Interfaces, Potsdam/Golm, Germany, [email protected]
2 Institute of Biocolloid Chemistry, Vernadsky av. 42, 03142 Kiev, Ukraine 3 Institute of Colloid Chemistry and Chemistry of Water, 03680 Kiev, Ukraine
4 Donetsk Medical University, 16 Ilych Avenue, Donetsk 83003, Ukraine
The interfacial tension of aqueous surfactant solutions against air (W/A), against hexane as bulk
phase (W/H) as well as against hexane vapor was measured by Drop Profile Analysis Tensiometry
(PAT-1, Sinterface Technologies, Germany) for decyl, dodecyl, tetradecyl and hexadecyl trimethyl
ammonium bromide (C10TAB, C12TAB, C14TAB and C16TAB). The obtained equilibrium interfacial
tension isotherms are interpreted by different thermodynamic adsorption models, out of which the
Frumkin Ionic Compressibility model1 appears to be the most suitable for the water/hexane interface.
It was earlier found2 that for the data at the aqueous solution/air interface, however, the reorientation
model is superior.
The water/hexane vapor interface appears as an intermediate situation between the W/A and the
W/H interfaces. The adsorption of the members of the homologous series CnTAB at their aqueous
solution/hexane vapour interface is a competitive process of surfactant and hexane molecules. The
presence of the hexane vapour results in a significant enhancement of the CnTAB adsorption as
compared with data obtained at the solution/air interface. A theoretical model for mixed adsorption
layers is shown to be capable of quantitatively describe the observed equilibrium adsorption
behaviour.
It is shown that the molar area of the surfactants is larger at the W/H interface as compared to
the W/A interface, and that this difference is getting smaller with increasing surfactant alkyl chain
length. The presence of hexane (as bulk phase as well as vapor phase) enhances the amount of
adsorbed CnTAB molecules3. There are no quantitative models that allow interpretation of the
interfacial dynamics yet, neither the adsorption kinetics in terms of dynamic interfacial tension nor the
dilational visco-elasticity.
1 V. Pradines, V.B. Fainerman, E.V. Aksenenko, J. Krägel, N. Mucic and R. Miller, (2010): Alkyltrimethylammonium
bromides adsorption at liquid/fluid interfaces in the presence of neutral phosphate buffer, Colloids Surfaces A 371, 22–28.
2 C. Stubenrauch, V.B. Fainerman, E.V. Aksenenko and R. Miller (2005): Adsorption behaviour and dilatational rheology of
the cationic alkyl trimethyl ammonium bromides at the water/air interface, J. Phys. Chem. 109, 1505 – 1509.
3 N. Mucic, N. Moradi, A. Javadi, E.V. Aksenenko, V.B. Fainerman and R. Miller, (2013): Mixed adsorption layers at the
aqueous CnTAB solution/hexane vapour interface; submitted
89
Nickel doped manganese oxide electrodes for redox supercapacitors
T. Nguyen1,2
, S. Eugénio1, R. Duarte
1,3, M.T. Silva
1,4, M.J. Carmezim
1,3, M. Boudard
2,
M. F. Montemor1
1 ICEMS, Instituto Superior Técnico, Universidade Técnica de Lisboa, Lisboa, Portugal
2 LMGP, Grenoble INP, CNRS(UMR 5628), MINATEC, 38016 Grenoble Cedex 1, France 3 Instituto Politécnico de Setúbal, Setúbal, Portugal
4 Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal
90
Shear-thickening properties of hydroxypropylmethyl cellulose/sodium
dodecylsulfate mixtures
Sandra Njaradi, Jaroslav Katona, Lidija Petrović
Faculty of Technology, University of Novi Sad, Novi Sad, Serbia, [email protected]
Interaction between hydroxypropylmethylcellulose (HPMC), a nonionic associative polymer,
and sodium dodecylsulfate (SDS), an anionic surfactant, takes place when SDS concentration is
higher than the critical aggregation concentration (cac) and ends when SDS concentration is higher
than the polymer saturation point (psp)1. The interaction results in HPMC-SDS complex formation
which has a significant influence on rheological properties of HPMC/SDS mixture, and leads to a
characteristic dependence of the zero shear viscosity on SDS concentration2. In this work, influence of
shear rate on HPMC-SDS interaction was investigated. HPMC/SDS mixtures were prepared with SDS
concentrations varied from 0.00 to 2.50% wt, covering range before, within, and after the HPMC-SDS
interaction. HPMCs of different molecular weights were used, where concentration of HPMCs in the
mixtures was adjusted so that the overlap parameter c[] (where [] is the intrinsic viscosity, c –
HPMC concentration) was set to 3, 6, and 12. HPMC/SDS mixtures show a typical Newtonian plateau
at low shear rates, which is then, on further increase in shear rate, followed by an expected power low
decrease in viscosity. However, above a critical shear rate in HPMC/SDS mixtures of sufficiently
high overlap parameter and within a characteristic SDS concentration range, shear-thickening flow is
observed. The increase in viscosity is accompanied with an increase in the first normal stress
difference. The shear-thickening flow takes place in HPMC/SDS mixtures prepared with HPMCs of
all three molecular weights tested, and is primarily governed by the overlap parameter. On increase in
HPMC molecular weight magnitude of shear-thickening increases while the onset of the shear-
thickening flow takes place at lower critical shear rates. The shear-thickening flow is attributed to
shear-induced structure formation in HPMC/SDS mixtures.
1 Nystrom, B., Kjoniksen, A.-L., Lindman, B. (1996): Effect of temperature, surfactant, and salt on the rheological behavior
in semidilute aqueous systems of a nonionic cellulose ether. Langmuir 12, 3233-3240.
2 Katona, J. M., Sovilj V. J. (2008): Rheological investigation on dynamics and structure of separated phases in polymer-
mixture – ionic surfactant ternary mixtures. Carbohydrate Polymers 74, 193-200.
91
Dynamic properties of mixed nanoparticle/surfactant adsorption layers
Boris Noskov1, Pavel Yazhgur
1, Libero Liggieri
2, S.-Y. Lin
3, Giuseppe Loglio
4, Reinhard Miller
5,
Francesca Ravera2
1 Department of Colloid Chemistry, St.Petersburg University, St.Petersburg, Russia, [email protected]
2 CNR-Istituto per l'Energetica e le Interfasi, Genova, Italy, [email protected] 3 Department of Chem. Eng., National Taiwan University of Science and Technology, Taiwan, [email protected]
4 Department of Organic Chemistry, University of Florence, Italy, [email protected] 5 MPI of Colloid and Interface Science, Germany, Reinhard. [email protected]
The behaviour of nanoparticles at liquid – fluid interfaces depends on the extent of their
hydrophobicity and can be similar in some respects to that of conventional surfactants. At the same
time, the adsorption layers of nanoparticles were investigated to a less extent because of the later
interest to these systems. In particular, the information on the surface rheological properties of the
dispersions of nanoparticles is scarce. In this work the adsorption films of silica nanoparticles
modified by a cationic surfactant (cetyltrimethylammonium bromide, CTAB) at the air-water
interface were investigated by the dilational surface rheology and optical methods. Special attention
was paid to the slow changes of surface properties with the surface age. The surface tension and
dynamic dilational surface elasticity were measured as a function of CTAB concentration. The whole
surfactant concentration range can be divided into four regions characterized by different surface
rheological behavior. Depending on the CTAB concentration, the surface elasticity close to the
equilibrium may reach extremely high values (~ 1000 mN/m) and strongly depends on the applied
surface strain. This occurs at surfactant concentrations below the region where the dispersion becomes
turbid, indicating particle aggregation in the bulk. The Brewster angle microscopy and ellipsometry
show that the adsorption layer becomes fragile and inhomogeneous in this region.
92
The impact of hop products on beer foam
Pavel Novák1, Martin Baszczyňski
1, Petr Linhart
2, Tomáš Brányik
2, Marek Růžička
1
1Institute of Chemical Process Fundamentals of the ASCR, v.v.i., Prague, Czech Republic, [email protected]
2Institute of Chemical Technology Prague, Prague, Czech Republic
Hop products have been lately used in brewing industry as replacement of leaf hops. The
increasing use of these products in beer production is supported by their chemical stability, better
storage and easier dosing as compared to leaf hops. Most of these products affect beer foam. The aim
of this work was to assess the impact of selected hop products, their concentration, pH and surface
tension on the foam structure and stability in matrices of model solution, model beer and real
commercial beer. Each sample was used to create foam in a defined way and the foam was analyzed
by image analysis and by the NIBEM-T method (Haffmans). The analyses led to structural and
stability characteristics of foams.
93
A Mechanistic Wall Heat Flux Partitioning Model of Nucleate Boiling
Under Impinging Jets
Ahmed M.T. Omar and Mohamed S. Hamed
Thermal Processing Laboratory, Department of Mechanical Engineering, , McMaster University, Hamilton, Ontario, Canada
This lecture presents details of an experimental investigation of boiling heat transfer under
impinging water jets. An experimental approach has been adopted to develop a mechanistic wall heat
flux partitioning (WFP) model of nucleate boiling under impinging jets. Bubble dynamics has been
investigated using high-speed imaging and an intrusive optical probe. This approach allowed the
development of the required closure sub-models of the mechanistic wall flux partitioning model. The
developed sub-models incorporated the effects of bubble generation frequency, bubble diameter and
bubble density considering the following conditions: jet velocity 0.4-1.7 m/s, water sub-cooling 10-28
°C and surface superheat 0-30 °C. The developed WFP model, incorporating the proposed sub-
models, has been used to predict the local rate of heat transfer at stagnation and at up to ten jet widths.
Overall agreement between the proposed WFP model and the experimental heat flux is within ±30%.
94
A Computer-Aided Molecular Design Approach for the Synthesis of
Novel Chemicals and Mixtures
Athanasios I. Papadopoulos1, Panos Seferlis
1,2, Spyros Voutetakis
1
1 Chemical Process and Energy Resources Institute, Centre for Research and Technology Hellas, Thessaloniki, Greece,
[email protected], [email protected] 2 Department of Mechanical Engineering, Aristotle University of Thessaloniki, Greece, [email protected]
This work presents an optimization-based Computer-Aided Molecular Design (CAMD)
approach to the development of novel chemicals and mixtures. The method employs group
contribution (GC) models which are based on the experimentally measured contributions of chemical
functional groups to the properties of particular molecules. This supports the development of
transferable structure-property links which are used in reverse formulations to identify molecules or
mixtures with desired characteristics. Molecules are described as a set of functional groups allowed to
link together based on connectivity constraints imposing chemical principles to establish feasible
structures. GC models facilitate the calculation of pure component (e.g. boiling point, surface tension
etc.) and complex mixture properties (e.g thermodynamic equilibria etc.). Utilizing molecular
characteristics as performance measures within an optimization-based formulation the method enables
the synthesis of novel molecular structures or conventional but previously overlooked molecules. The
resulting molecules exhibit optimum features in a wide range of chemical, physical, environmental,
safety or other properties. They are subsequently introduced in models representing the application
systems in which they will be utilized, using information extraction methods to avoid tedious
computations. This enables the evaluation of their impact in the economic performance of their host
systems as well as the identification of optimum system features that best fit each molecule/mixture.
The presented technology enables the fast and reliable evaluation of a vast number (millions) of
characteristics leading to efficient chemicals. It is illustrated in the development of new pure and
mixed fluids for efficient power generation from renewable energy sources using Organic Rankine
Cycle (ORC) systems1,2
. Such systems are receiving increased attention as they are reasonably
compact and flexible, enabling power generation from low-enthalpy sources. Their operation is based
on the vaporization of a single or mixed working fluid to drive a turbine, hence the characteristics of
the employed fluid have a direct and major impact in the system performance. Numerous molecular
properties are considered as important performance measures during CAMD including viscosity,
thermal conductivity, molar heat capacity, heat of vaporization, flammability, toxicity and so forth.
The resulting fluids indicate higher economic and operating performance than conventional choices.
This work further explores the potential of implementing CAMD methods in the development
of polymer materials. Numerous applications require polymers that exhibit high performance in
several important properties such as endurance to increased temperatures, increased safety and high
selectivity or permeability toward specific compounds, to name a few. CAMD can be used to
investigate and identify materials that can replace conventional options and improve the performance
of products or applications in which polymers are utilized.
1 Papadopoulos, A.I., Stijepovic, M., Linke, P., Seferlis, P., Voutetakis, S., (2012): Multi-level design and selection of
optimum working fluids and ORC systems for power and heat cogeneration from low enthalpy renewable sources.
Computer-Aided Chemical Engineering 30, 66-70.
2 Papadopoulos, A.I., Stijepovic, M., Linke, P. (2010): On the systematic design and selection of optimal working fluids for
Organic Rankine Cycles. Applied Thermal Engineering 30, 760-769.
95
Effect of different tissue surfaces on decompression induced bubble
growth from gas saturated solutions
Virginie Papadopoulou 1,2
, Sotiris Evgenidis 3, Robert J. Eckersley
4, Costantino Balestra
2,5,
Meng-Xing Tang 1, Thodoris Karapantsios
3
1 Department of Bioengineering, Imperial College London, London, UK, [email protected]
2 Environmental & Occupational Physiology Lab. Haute Ecole Paul Henri Spaak, Brussels, Belgium 3 Department of Chemistry, Aristotle University of Thessaloniki, Thessaloniki, Greece
4 Imaging Sciences & Biomedical Engineering Division, King's College London, London, UK 5 DAN Europe Research Division, Belgium
Decompression illness (DCI) is a pathophysiology caused by bubbles1 which grow in the body
during or after a reduction in ambient pressure (decompression) that can affect divers, astronauts,
pilots and compressed air workers.
Gas bubbles are not uncommon, and have been observed to form in the body after most scuba
dives, even those which follow the recommended protocols conservatively2. These can sometimes
trigger DCI whose symptoms vary in severity from the simple skin rash to coma or death. With
around 7 million active recreational scuba divers worldwide and more extreme forms of diving
becoming popular3, understanding the process of physiological bubble formation is particularly
important.
The study of bubble formation and growth in vivo, of which little is known to date4,5
, can
improve preventive measures against DCI and is also relevant in physiology as an example of
adaptive response to extreme environmental stress, and more broadly for hyperbaric oxygen treatment
and to study the degree of tolerated embolism to the body, with broad medical applications
(ultrasound microbubble contrast agents or surgical and mechanical ventilation embolism risks, as
well as skin transplants applications).
After introducing the topic and aim of this research, a new experimental set-up that allows the
recording of bubble growth on tissues during hyperbaric decompression is presented. It allows the
observation of the growth rate of selected bubble, but also bubble density per unit surface area,
comparing how these vary for different tissue surfaces, decompression profiles and gas saturated
liquid composition.
1 Levett, D.Z.H., Millar, I.L. (2008); Bubble trouble: a review of diving physiology and disease. Postgrad Med J 84:571-578,
2008.
2 Spencer. M.P. (1976); Decompression limits for compressed air determined by ultrasonically determined blood bubbles. J
Appl Physiol 40:229-235.
3 Vann, R.D., Freiberger, J.J., Caruso, J.L. (2005); Divers alert network report on decompression illness, diving fatalities and
project dive exploration: 2005 edition (based on 2003 data). DAN Technical report
4 Papadopoulou, V., Eckersley, R.J., Balestra, C., Karapantsios, T., Tang, M.-X. (submitted 2012); A Critical Review of
Physiological Bubble Formation in Hyperbaric Decompression. Advances in Colloid and Interface Science, Submitted.
5 Blatteau, J.-E., Souraud, J.-E., Gempp, E., Boussuges, A. (2006); Gas Nuclei, Their Origin, and Their Role in Bubble
Formation. Aviat Space Environ Med 77:1068 –1076.
96
Laser beams interaction with droplets in pendant position
Mihail-Lucian Pascu, Mihai Boni,Viorel Nastasa, Agota Simon, Andra Dinache, Ionut-Relu Andrei
Laser Department, National Institute for Laser, Plasma and Radiation Physics, Bucharest, Romania;
email: [email protected]
The interaction of distilled water droplets (having volumes of 3-4 µl) in pendant/hanging
positions in air, with pulsed laser beams emitted at 532 nm is described. At 532 nm the distilled water
absorption is very low and the interaction of a water droplet with the laser radiation is dominated by
unresonant phenomena, i.e. laser beam is not absorbed by the droplet’s content.
In this case, following the collision of the laser beam, on the droplet are produced deformations
as well as mechanical vibrations. The conditions in which the droplets lose material as a consequence
of the impact with laser beams are explored and introduced. The effects produced on the droplet were
studied pulse by pulse and depend on: the droplet’s content, the beam wavelength, power and
focusing, the irradiation geometry and the adhesion of the droplet to the capillary on which it is
suspended. The laser pulses energies were varied in four steps: 0.25 mJ, 0.4 mJ, 0.7 mJ and 1 mJ. The
laser pulse full time width at half maximum was 5ns and the typical beam waist diameter on the
droplet was 90µm which was kept for about 300µm. because the beam had a relatively low
divergence around the focus point.
The droplet’s shapes evolution was visualized by recordings performed at 10 kframes/second.
Following a droplet interaction with the laser beam one may also produce at a controlled moment in
time, nanodroplets propagating at high (probably supersonic) speeds and microdroplets propagating at
slower speeds. One may also produce suspended droplets of smaller dimensions than the initial one as
well as micro/nano gas bubbles in the suspended droplet’s material/volume.
In a second set of experiments the behaviour of the microdroplets of Rhodamine 6G in distilled
water was recorded at high speed, at resonant interaction with similar laser pulses, and at the same
power levels. The phenomena considering that the droplets contents are Newtonian liquids produced
at interaction with the laser beams, are discussed1.
A discussion is made about the relation between the unresonant and resonant interaction of the
laser beams with microdroplets, from the point of view of mechanical effects and optical effects
induced in the droplet.
1M. L. Pascu, G V. Popescu, C. M. Ticos, I. R. Andrei (2012): Unresonant interaction of laser beams with
microdroplets. J. Europ. Opt. Soc. Rap. Public. 7, 12001.[DOI: http://dx.doi.org/10.2971/jeos.2012.12001]
97
Photocatalytic hydrogen evolution under visible light over CdSeS
Imren Hatay Patir 1, Emre Aslan
1, Canan Baslak
1, Okan Birinci
2, Mahmut Kus
2, Mustafa Ersoz
1
1Department of Chemistry, Selcuk University, Konya, Turkey, email: [email protected]
2
Selcuk University Advanced Technology Research&Application Center, Konya, Turkey.
Hydrogen is considered to be a potential candidate for a non-polluting energy source due to its
environmental friendly and renewable characteristics. Photocatalytic H2 production from water
splitting using semiconductor photocatalysts has drawn considerable attention as a promising way of
resolving global energy and environmental problems. The development of visible-light driven
photocatalysts is indispensable for the utilization of the main part of the solar spectrum, which is of
great importance for the practical application of the semiconductor photocatalytic system [1].
Until now, cadmium sulphide (CdS) and cadmium selenide (CdSe) nanoparticles have been
reported to generate hydrogen in the semiconductor photocatalyts system. But there is no any report to
showing the catalytic activity of CdSeS alloys.
In this study, we present the catalytic properties of CdSeS towards hydrogen evolution from
water phase. This catalytic process is studied by gas chromatography. The results demonstrate that
CdSeS alloys show better activity than CdSe and CdS core nanoparticles.
1 Xu Zong, Jingfeng Han, Guijun Ma, Hongjian Yan, Guopeng Wu, and Can Li, J. Phys. Chem. C 2011, 115, 12202–12208 2 F. Andrew Frame, Elizabeth C. Carroll, Delmar S. Larsen,Michael Sarahan,Nigel D. Browningb and Frank E. Osterloh,
Chem. Commun., 2008, 2206–2208
98
Interfacial characteristics of colloidal dispersions:
The apparent wall slip and its detection
Věra Pěnkavová, Ondřej Wein
Department of Multiphase Reactors, Institute of Chemical Process Fundamentals of the ASCR, v.v.i., Prague, Czech
Republic, [email protected]
Studying the flow of colloidal dispersions in confined configurations, one should be careful
about possible anomalous behavior at solid-liquid interface. Concentration of disperse phase in
proximity to the wall can decrease due to steric reason or other reasons and, as a result, a
concentration gradient and corresponding changes of local viscosity are set. Then the flow close to the
wall takes place at essentially lower viscosity than viscosity in the bulk flow. This effect is called the
apparent wall slip1 (AWS) and can be characterized by slip velocity as a function of applied shear
stress. The macroscopically observable effect of AWS depends on the gap thickness: the smaller gap
thickness the larger change of flow rate. In the viscometry with extremely thin gaps, the neglect of
AWS slip can result in misinterpreting of primary viscometric data.
In this contribution we describe methodology, called AWS viscometry2, which enables us to
detect both viscosity of colloidal dispersion and slip coefficient which characterizes the flow behavior
at solid-liquid interface. Due to dependence of AWS contribution to flow on gap thickness we can
detect both viscosity and slip coefficient via viscometry measurements done at various gap
thicknesses for the same shear stress. Treating data using nonlinear regression enables us to detect
both viscosity and slip coefficient. Therefore we are able to describe full behavior of colloidal
dispersion flowing around solid wall. Principles of AWS viscometry are shown on example of
aqueous kaolin dispersions.
1 Barnes, H. A. (1995): A rewiew of the slip (wall depletion) of polymer solutions, emulsions and particle suspensions in
viscometers: its cause, character and cure. Journal of Non-Newtonian Fluid Mechanics 56, 221-251.
2 Wein, O., Vecer, M., Tovcigrecko, V. V. (2006): AWS rotational viscometry of polysaccharide solutions using a novel KK
sensor. Journal of Non-Newtonian Fluid Mechanics 139, 135-152.
99
Kinetics of hydration of carbonated shell on surface of NaAlSi glass fibers
Evalds Pentjuss, Andrejs Lusis, Gunars Bajars, Jevgenijs Gabrusenoks
Institute of Solid State Physics, University of Latvia, [email protected]
Glass fiber fabrics are used in dry and wet atmosphere and in water at elevated and changeable
temperatures. The changes of environment conditions may initiate processes in the glass fibers that
lead to a new its equilibrium state and changed physical properties of fabric. Some of them may be
irreversible. It is accepted [1,2] that interaction of alkali silicate glasses with water or mineral acids
proceeds by ionic exchange by diffusion of Na+ ions to glass surface and H
+ or H3O
+ from water into
the bulk of material to fill the vacancies of Na+ ions. It looks that Na
+ ions and H2O and CO2 from
atmosphere form the shell of Na2CO3·H2O and Na3H(CO3)2·2H2O mixture on the surface of
elementary glass fibers. Such shell can be dissolved in water and acids (leached) and decomposed
partly and/or dehydrated by heating [3]. There are studied the weight loss of leached and not leached
fabric of K-glass [composition: (18-22)Na2O·(3-5)Al2O3·(73-79)SiO2] after heating at different
temperatures and followed long term weight recovery process at room conditions. The experimental
weight recovery- time curves were fitted to exponential regression function of
M (t) = M0-M1 exp (-t/T1)-M2 exp (-t/T2),
that characterizes the sample weight M(t) increase by two additive mechanisms. Here (T2≥T1). The
parameters M1, T1 characterize the first mechanism and M2, T2 the second one. The experimental
weight recovery-time curves of leached and non leached (having a shell) samples show increased an
irreversible weight loss in samples heated before at elevated temperatures. The irreversible weight
loss has to be associated with the loss of Na+ ions and partly destruction of the shell. As a result the
absorption of CO2 is not prospective. Regression analysis shows that weight increasing after heating
are well described (R2
> 0,99) in time intervals during weight stabilization time by exponential
function written above. For the samples with a shell, the values of T1 increase from 0,017 h- 0,04 h
and T2 increase from some hours to 125 h (for sample heated at higher temperatures) and to 255 h (for
less heated samples ) for later t = 100 h. The both processes are going simultaneously. Leached and
more heated sample has only one T1 (about 0,096 h) process of the early weight increasing. Such
results lead to an opinion that T1 process at the beginning of weight stabilization characterizes the
velocity of water absorption on the surface determined by surface roughness and process T2
characterizes the leaving of water molecules from surface into volume (probably by diffusion), that
allows to absorb next water molecules and to continue restore the weight. Then the late T2
characterizes the saturation with water the all volume of shell. For its part an increase of early T1
along heating temperature characterizes an increase of surface roughness of carbonated shell and glass
fibers (in a case of leached samples) and late T2 the volume loss.
[1] Veal B.W., Lam D.J., Karim D.P. (1980) Nuclear Technology 51, 136.
[2] Tsong I.S.T., Houser C.A., White W.B., Power G.L., Tong S.S.C. (1980) Non-Cryst.Solids 38-39, 649.
[3] Pentjuss E., Lusis A., Bajars G., Gabrusenoks J., Jekabsone L. (2012) IOP Conf. Series: Materials Science and
Engineering 38, doi:10.1088/1757-899X/38/1/012021.
100
Ecotoxicity assessment of surface modified alumina nanoparticles on
V. fischeri
Maria D. Petala, Vasilios Tsiridis, Efthymios Darakas
Division of Hydraulics and Environmental Engineering, Department of Civil Engineering, Aristotle University of
Thessaloniki, 54124 Thessaloniki, Greece, [email protected]
Environmental risks posed by engineered nanomaterials (ENMs) are of major concern and are
currently estimated by numerous ecotoxicity tests. The complex nature and behavior of ENMs has led
to the adoption of customized experimental ecotoxicity practices, thus even enabling the possible
introduction of artefacts to the inherent toxic properties of ENMs. In addition, the lack of standardized
ENMs handling procedures for ecotoxicity testing prevents the development of experimental
protocols for regulatory purposes. To investigate whether the ENMs handling affects their ecotoxic
properties, a suite of ENMs dispersion techniques was adopted and tested. For this purpose, two
surface modified alumina nanoparticles (OS1 and OS2, Sasol) were dispersed to water and subjected
to ecotoxicity testing towards bacteria Vibrio fischeri. Several factors including the mixing duration,
the salinity of the dispersion water, the initial tested concentration of ENMs and the centrifugation of
the obtained dispersions were examined, in order to assess the handling implications to the resulted
ecotoxic effects on V. fischeri. The results of this study highlight a number of issues concerning the
ecotoxicological risk assessment. Briefly, it is discussed how and to what extend the aforementioned
factors affected the toxicity of the tested ENMs.
101
Experimental and Numerical Investigations
into the Coating Process of a Single Particle
Bernhard Peters1, Alidad Amirfazli
2
1Université du Luxembourg, 6, rue Coudenhove-Kalergi, L-1359 Luxembourg, Luxembourg, [email protected]
2York University, Department of Mechanical Engineering, York University, Toronto, ON, M3J 1P3, Canada,
One of the fundamental steps in the fluidized bed (FB) process is characterized by collision
between a liquid drop and a particle. This is facilitated by atomizing and injecting a liquid into
fluidized bed made of particles. Important parameters are size ratio, shape of the particle, its
wettability; drop properties and collision conditions. However, very little concrete experimental and
verified numerical information is available as to what are the relevant factors to facilitate uniform
coverage of particles by drops.
An apparatus was built to allow deterministic impact of a particle and drop to occur in midair.
Using high speed imaging the impact of three different particles with water drops is studied at
different relative velocities (see Fig. 1a). Possible collision outcomes are elucidated in terms of
particle-drop diameter ratio, Weber number, and particle wettability. Three distinct regimes of
bonding, ripping and coating, and shattering are identified and discussed in this novel study.
In conjunction with experiments the impact of a drop onto a particle is studied numerically
using the interface compression and interface reconstruction in a multiphase flow approach using
open-source code OpenFoam. Such simulations support the understanding of underlying physics and
allows for examining various factors mentioned above efficiently. In a first step a two-dimensional
system with a contact angle of 80° was used. A qualitative comparison between experimental and
numerical results shown in Fig. 1 demonstrates a satisfactory agreement. Thus, the future research
will focus on extending the numerical studies to a fully three-dimensional approach where both
interfaces liquid-solid and liquid-air can be examined in detail to better understand the coating
process.
(a) (b)
Figure 1 – (a) Image showing the drop-particle configuration (“bonding”) after an impact event
obtained by measurements and numerical simulations. The drop was water and particle was Nylon
with contact angle of ~90 degrees. The head-on collision relative velocity was 1.5 m/s. (b) head-on
collision of drop and particle (contact angle 80 deg.) with relative velocity of 0.5 m/s
102
Particulates for stabilizing foams and emulsions: the challenges remain
Jordan Petkov
Unilever R&D Port Sunlight, Quarry Road East, Bebington, Wirral, CH63 3AH, United Kingdom,
Since Pickering1 has published his successful attempt to stabilize oil by using CaSO4 and
CuSO4 particulates many scientists have tried to follow up in his steps and apply the same (or similar)
approach to more challenging systems. Particle stabilized foams or emulsions are still a very attractive
option despite the failures of many to achieve long term stability in the presence of even tiny amounts
of surfactants. The desire to get a formulation stabilized only by particulates that could have extra
function, beside their stabilizing power, is still the main driver for people entering the field and
exploring opportunities for their wider applications.
With the plethora of newly synthesized particles bearing new functionalities and reduced
surfactant sensitivity, the hopes that this might become possible have gone up. In my presentation I
will try to summarise the available practical solutions and consider them in the light of potential
industrial use, away from the bench in a real working environment.
1 Pickering, S.U., (1907): The Chemistry of Bordeaux Mixture. Journal of Chemical Society: Transactions 91, 1988-2001.
103
Flow behavior of complex interfaces: the case of surfactant vesicles
Angelo Pommella1, Sergio Caserta
2, Stefano Guido
3.
Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale,
University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy. 1 [email protected], 2 [email protected], 3 [email protected]
In several applications, from detergents to foodstuff and pharmaceuticals, the dispersed phase
of liquid-liquid systems is made of “complex” droplets which are endowed with their own internal
microstructure (e.g., liquid crystalline, gel-like, compound droplets)1,2
. Here, we review the literature
in this field and then focus on the case of surfactant multilamellar vesicles (SMLVs)3, which are
characterized at rest by an almost spherical structure consisting of onion-like stacked bilayers
separated by solvent molecules. While many studies have been so far addressed to the phase behavior
of surfactants in water, only limited information is available in literature on flow-induced morphology
of such systems.
In this work, single SMLVs are investigated under simple shear flow by using a video-
microscopy rheo-optical apparatus. Two different setups allow the observation of the sample both
along the vorticity and velocity gradient directions. As with liquid droplets, SMLVs are deformed and
oriented by the action of shear flow while keeping constant volume, but exhibit complex dynamic
modes (i.e., tumbling, breathing and tank-treading) which are typical of unilamellar vesicles. The
analogies and differences with the behavior of isolated droplets and capsules is discussed on the basis
of non-dimensional scaling parameters. Furthermore, the results are interpreted in terms of the internal
microstructure of SMLVs as visualized by 3D reconstruction of confocal microscopy images.
1 M. M. Fryd and T. . Mason, “Advanced Nanoemulsions”, Annu. Rev. Phys. Chem., 63, 493–518 (2012)
2 M. Simeone, M. Tassieri, V. Sibillo and S. uido, “Effect of sol-gel transition on shear-induced drop deformation in
aqueous mixtures of gellan and k-carrageenan”, J. Colloid nterface Sci., 281, 488-494 (2005)
3 A. Pommella, S. Caserta, V. uida and S. uido, “Shear-induced deformation of surfactant multilamellar vesicles”, Phys.
Rev. Lett., 108, 138301 (2012)Chang, C. H., Franses E. I. (1995): Adsorption Dynamics of Surfactants at the Air/Water
Interface - a Critical Review of Mathematical Models, Data, and Mechanisms. Colloids Surfaces A - Physicochem Eng
Aspects 100, 1-45.
104
HORIZON 2020 Programme:
Opportunities for research funding protection
and exploitation of research results
Petr Pracna, Jana Kratěnová
Technology Centre ASCR, Prague, Czech Republic, [email protected], [email protected]
The talk gives an overview of two topics related to project proposals to the new EU framework
programme Horizon 2020 scheduled for the years 2014-2020. The first part focuses on a certain
restructuring of the programme priorities from the 7th Framework programme (FP7) towards the
Horizon 2020 programme whose goals are identified in the EUROPE 2020 strategy as smart,
sustainable and inclusive growth. The priorities address in a larger extent enabling technologies and
societal issues in which excellent science will be playing a dominant role. Brief information on
Horizon 2020 and FP7 project calls within fields relevant to the conference audience will be provided
as well.
As soon as project calls are announced, partners usually start to prepare their project proposals.
At this stage partners should focus not only on research work plan but also on Intellectual Property
(IP) issues as these also should be obligatorily addressed in project proposals. Therefore the second
part of the talk will be devoted to explanation of basic principles of Horizon 2020 IP rules (definition
of background and results including access rights; results protection, exploitation and dissemination)
and comparison to the FP7 ones with special focus on research results exploitation and currently
widely discussed issue of open access to data.
105
Experimental Investigation of Phase Inversion for Stable Emulsion
Formation
Valentina Preziosi1, Antonio Perazzo
2, Sergio Caserta
3, Giovanna Tomaiuolo
4, Stefano Guido
5
Dipartimento di Ingegneria Chimica dei Materiali e della Produzione Industriale,
University of Naples Federico II, P.le Tecchio 80, 80125 Naples, Italy. [email protected], [email protected], [email protected], [email protected],
Emulsions are metastable systems, composed at least of two immiscible phases, and are
relevant for many industrial applications and for several products like pharmaceuticals (e.g.,
microemulsions and vesicles for drug delivery), foodstuff (e.g. ice cream, mayonnaise), detergents
etc. Some of the physical mechanism leading to emulsion phase separation are: i) coalescence, ii)
collision, iii) Ostwald ripening, iv) creaming & sedimentation. To stabilize emulsions, surface active
agents, molecules with an amphiphilic character, are added in order to decrease interfacial tension
between the two phases. The classical emulsion preparation process consists in dissolving the
surfactant in the continuous phase, in which it has to be soluble, and to add the dispersed phase under
appropriate agitation. An alternative preparation method, known since fifties, but where a deep
understanding still lack, is based on the phase inversion1,2,3,4,5
, a process whereby water-in-oil (W/O)
emulsion inverts into an oil-in-water (O/W) and vice versa to produce fine emulsions by low energy
stirring. In this work we describe the formation of stable emulsions by phase inversion. Static optical
and confocal image and have been acquired in order to characterize phase transition.
1 Shinoda, K., Arai, H. (1964), The correlation between phase inversion temperature in emulsion and cloud point in solution
of nonionic emulsifier, J Phys Chem, 68, 3485-3490.
2 Fernandez, P., André, V., Rieger, J., Kuhnle A. (2004), Nano-emulsion formation by emulsion phase inversion, Coll Surf
A, 251, 53-58.
3 Liu, L., Matar, O.K., Perez de Ortiz S., Hewitt, G.D. (2005), Experimental investigation of phase inversion in a stirred
vessel using LIF, Chem Eng Sci, 60, 85-94.
4 Sajjadi S., (2006), Nanoemulsion formation by phase inversion emulsification: on the nature of inversion, Langmuir, 22,
5597-5603.
5 Galindo-Alvarez, J. G., Sadtler, V., Choplin, L., Salager J. (2011), Viscous Oil Emulsification by Catastrophic Phase
Inversion: Influence of Oil Viscosity and Process Conditions ,Ind Eng Chem Res, 50, 5575-5583.
106
RF-plasma and UVC Pretreatment of Surfaces: Self-cleaning and
Antimicrobial Effects
C. Pulgarin1, J. Kiwi
1, R. Sanjines
2
*Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-ISIC-GPAO, Station 6, CH-1015, Lausanne, Switzerland
‡Ecole Polytechnique Fédérale de Lausanne, EPFL-SB-IPMC-LNNME, Bat PH, Station 3, CH-1015, Lausanne, Switzerland
Two new innovative findings presented in this study are: a) TiO2-cotton fabrics obtained by
pretreatment with UVC light (185 nm) at atmospheric pressure introduced functionalities into the
cotton surface enabling the chelation/binding of TiO2. This was possible since the molar absorption
coefficient of O2 and N2 is very low at 185 nm and b) the radiofrequency (RF-plasma) pretreatment of
cotton surface lead to the formation active binding sites on the cotton at atmospheric pressure. This
unexpected RF effect was due to the drastic localized heating of the cotton leading to intermolecular
H-bond breaking between the cellulose surface-OH groups of adjacent molecules with the formation
of functionalized groups in the cellulose fibers. The discoloration kinetics of the wine stain on the
TiO2-cotton pretreated by RF at atmospheric pressure for 10 min was the most favorable. The red
wine stains discoloration under Suntest simulated light was monitored by Diffuse Reflectance
Spectroscopy (DRS) and by the CO2 evolution during the stain mineralization. By X-ray
photoelectron spectroscopy (XPS) it was possible to monitor the decrease of the C, N, and S-species
on the textile topmost layers during the discoloration process. The XPS Ti2p3/2 peak shifts indicating
Ti4+
/Ti3+
oxido-reduction taking place during the photocatalysis. X-ray diffraction showed the
formation of the anatase phase on the cotton. By X-ray fluorescence the loading of TiO2 before and
after the discoloration process was found to be 0.8%. High-resolution electron microscopy
(HRTEM) shows transparent TiO2 anatase 8-18 nm coating the cotton with layers 31 nm ( 10%).
These 3-4 TiO2 layers on the cotton did not affect the touch or handling properties of the cotton
enabling the potential commercial use of the TiO2-cotton fabrics.
1Bozzi, A., Yuranova, T., Kiwi, (2005) J. Self-cleaning of Wool-polyamide and Polyester Textiles Due to Surface TiO2-rutile
Modification Under Daylight Irradiation. A. Bozzi, T. Yuranova and J. Kiwi, J. Photochem. Photobiol. A 172, 27-34.
2Meilert, K., Laub, D., Kiwi, J. (2005) Photocatalytic Self-cleaning of Modified Cotton Textiles by TiO2 Clusters Attached
by Chemical Spacers, J. Molec. Catal. A., 237, 101-108.
3Mejía, M., Marín, J., Restrepo, G., Pulgarín, C., Mielczarski, E., Mielczarski, J., Arroyo, Y., Lavanchy, J. C., Kiwi, J (2009).
Self-cleaning TiO2 cotton pretreated by RF-plasma and UV-C-light (185 nm) in vacuum and also under atmospheric
pressure. Appl. Catal. B, 91, 481-488.
4Mejía, M., Marín, J., Restrepo, G., Pulgarín, C., Mielczarski, E., Mielczarski, J.,Kiwi, J (2009). Self-cleaning of pretreated
Nylon by UVC-light (185 nm) and plasma RF under atmospheric pressure., ACS Applied Materials and Interfaces, 1, 2190-
2198.
107
Smart & Green interfaces meet EU policy
Jean-Francois Renault1
1 Dpt. International / Consulting / Strategy, Div. Technology transfer and Business setting,
Project Management Juelich (PtJ), Germany, [email protected]
Horizon 2020 will be soon reality. More than ever excellent research and development is not
enough. R&D results have to be implemented on the market and the society. The best way to achieve
this objective is to be well visible, understood, and supported. How to do that?
There are plenty of experience from FP7 (and earlier FPs) as well as from other European
funding programmes and even not European programmes on bringing the Innovation community and
the Policy makers together.
We will consider three aspects of the “meeting process”: contents, tools and target audience.
The first step needs an analysis in depth on how the topic considered contributes to the main policy
papers of the moment. That would mean today for example: how to we help meeting the global
challenges, implementing Europe 2020 and EcoAP? Where are the benefits for the society, for the
policy makers…?
The second step is more practical: which tools are the most effective? “Policy briefs” on the
OECD model?, “Recommendation papers, Roadmaps?”, “Electronic news?, “List of best practices,
observatory and scoreboard?, “ sing social networks?”… We should develop a tailor made mix of all
these tools!
The last point is maybe the more crucial one. The final target audience is clear: the EU policy
makers. But what about all the multipliers, working groups, lobbyists…?
Bringing R&D results on Smart & Green interfaces to EU policy is a long way but it works and
it is worth! All Aboard!
108
Microstructural evolution of ball-milled Mg-Ni powder during
hydrogen sorption
Á. Révész
Department of Materials Physics, Eötvös University, Budapest, H-1518, P.O.B. 32, Budapest, Hungary
email: [email protected]
Magnesium is considered as one of the most attractive hydrogen storage materials, mainly
because of high storage capacity (7.6 wt.%), lightweight and low cost. Nevertheless, high
thermodynamic stability, high hydrogen desorption temperature and relatively poor hydrogen
absorption-desorption kinetics at temperatures below 350oC impedes the use of Mg in industrial
applications. To improve the hydrogen storage properties of magnesium, nano-sized Mg powders
have been produced by mechanical alloying. Among Mg-based alloys, binary Mg-Ni is the most
remarkable due to its favorable thermodynamics.
In the present work, ball-milling blends of commercial polycrystalline Mg and Ni powders was
carried out using a SPEX 8000 Mixer Mill for different durations ranging from 1 to10 hours. X-ray
powder diffraction experiments indicated that milling up to 10 h results the formation of stochiometric
hexagonal Mg2Ni line compound.1 Morphology studies were performed on a FEI QUANTA 3D dual
beam scanning electron microscope. The compositional changes were quantified by energy dispersive
X-ray analysis. Repeated dehydriding-hydriding cycles were carried out in a Sievert’s-type apparatus.
In order to characterize the microstructural changes during a complete dehydriding transformation, the
3rd desorption was interrupted at different hydrogenation stages (25, 50 and 75% of de-
hydrogenation). Convolutional Multiple Whole Profile fitting analysis of the corresponding X-ray
diffractograms was applied to reveal the evolution of competiting phases and the microstructural
parameters, such as average coherent domain size, lattice strain and lattice parameter.2
1Á. Révész, Zs. Kánya, T. Verebélyi, P.J. Szabó, A.P. Zhilyaev, T. Spassov J. Alloys Compd. 504 (2010) 83-88
2 Á. Révész, M. Gajdics, T. Spassov, Int. J. Hydrogen Energy, submitted (2013)
109
Highly dense carbon monoliths with anomalously high volumetric
capacitances.
Jose M. Rojo1, A. Garcia-Gomez
1, V. Barranco
1, J. Ibañez
2, J. D. Carruthers
3, M. Kunowsky
4 and A.
Linares-Solano4
1 Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Madrid, Spain, [email protected]
2 Centro Nacional de Investigaciones Metalurgicas (CENIM), CSIC, Madrid, Spain. 3ATMI Company, USA.
4Dpartamento de Quimica Inorganica, Universidad de Alicante, Alicante, Spain.
Carbon monoliths showing high density (up to 1.2 g cm-3
), high electrical conductivity (9-10 S
cm-1
), high content of surface oxygen groups (up to 2411 µmol CO g-1
) and large specific surface area
(1000-1600 m2 g
-1), are studied as supercapacitor electrodes. Two-electrode cells having 2 M H2SO4
solution as electrolyte were used for the electrochemical study. The starting monoliths, which were
produced by ATMI Co, were additionally treated either under N2 flow at 800 ºC to modify the carbon
surface chemistry or under CO2 flow at that temperature to increase the specific surface area and
modify the micropore size distribution. The monoliths show specific (gravimetric) capacitances in the
range 240-300 F g-1
and volumetric capacitances in the range 230-350 F cm-3
. The volumetric
capacitances, which are the highest ever reported for porous carbon monoliths, are explained by the
high specific capacitance and high density of the monoliths.
110
Electrochemical performance of hierarchical carbon structures
materials obtained from lignin infiltration of zeolite templates
Ramiro Ruiz-Rosas1, M.J. Valero-Romero
2, J. Rodríguez-Mirasol
2, T. Cordero
2, E. Morallón
3, D.
Cazorla-Amorós1
1 Inorganic Chemistry Department, University of Alicante, Alicante, Spain, [email protected]
2 Chemical Engineering Department, University of Malaga, Malaga, Spain, [email protected] 3 Chemistry & Physics Department, University of Alicante, Alicante, Spain, [email protected]
Carbon materials with hierarchical pore structure have been prepared using the liquid phase
impregnation (LPI) technique with lignin solution as carbon precursor and Y and Beta zeolites as
templates. Lignin is the second most abundant biopolymer in nature and constitutes an underutilized
by-product traditionally of the papermaking industry and now also from the expanding cellulosic
ethanol one.
The obtained carbons have a bi-modal porous structure. They contain microporosity coming
both from the removal of the zeolite walls and lignin devolatilization, and a mesoporosity network
resulting from the removal of the non-infiltrated zeolite. The use of lignin as precursor results in
carbon materials with interesting surface chemistry features, such as nitrogen pyridone/pyrrolic and
pyridinic groups, and a variety of oxygen surface groups.
The electrochemical characterization in aqueous acid media revealed a high contribution of
pseudocapacitance in these materials and good capacitance retention when using high sweep rates and
specific currents. They can be easily in-situ electrooxidized, producing an increment of surface
oxygen groups that enhances the pseudocapacitance. This seems to be a consequence of the presence
of edge sites in the carbon fraction formed from the infiltration in the zeolite. The electrooxidized
carbon materials showed a capacitance as high as 280 F·g-1
at a current density of 50 mA·g-1
, while
being able to keep a capacitance of 155 F·g-1
operating at more than 20 A·g-1
thanks to their adequate
porous texture. These results point out the potentials of the use of biomass wastes, like lignin, as
carbon precursors in the production of hierarchical carbon materials for electrodes in electrochemical
capacitors.
111
Smart bionanostructures and interfaces via direct reaction of
functionalized catechols
Javier Saiz-Poseu1, Beatriz García
2, Josep Sedó
1, Jordi Hernando
3,
Felix Busqué3, Daniel Ruiz-Molina
1*
1Centro de Investigación en Nanociencia y Nanotecnología, Campus UAB, 08193, Cerdanyola del Valles,Spain,
[email protected] 2Fundación Privada ASCAMM, Unidad de Nanotecnología (NANOMM), ParcTecnològic del Vallès, Av.
UniversitatAutònoma, 23 - 08290 Cerdanyola del Vallès, Spain 3Chemistry Department, Universitat Autònoma de Barcelona, Campus UAB 08193, Cerdanyola del Vallès,
Spain
Mussel-adhesive proteins have been the subject of intensive scientific research associated to
their remarkable ability to strongly adhere to virtually all surfaces. This behavior has been attributed
to their varying amounts of the non-essential catecholic aminoacid DOPA1.
Herein we report a new synthetic approach for the fabrication of such catechol-based materials
with adherent properties. The mechanism is based on a simple polymerization process in the presence
of ammonia2, in a way reminiscent of melanization reactions. The initial molecule of choice was a
catechol bearing a long alkyl chain. The resulting material after polymerization, spontaneously self-
assembles in the form of nanoparticles that easily stick to different surfaces and materials. As an
application, the NPs have been successfully implemented for water remediation of heavy metal ions
and are being explored nowadays for drug delivery.
On the other side, when this material is placed in non-polar solvents such as hexane, the NPs
are dissolved and the polymer is used to obtain coatings thanks to their adhesive properties. Coatings
are effective on a representative variety of substrates, both at the nano-/macroscale, without any
pretreatment or interphase modification. Whereas a long alkyl chain affords coatings with a persistent
hydrophobic character, this methodology can be extended to several other catechols with different
ring pendant groups, providing additional surface functionalities such as oleophobic, anti-fouling or
anti-bacterial activities3.
1 Ruiz-Molina et al. et col. Adv. Mat. (2013), doi:10.1002/ adma.201202343
2 Ruiz-Molina et al. Adv. Mat. (2013), in press.
3 Ruiz-Molina et al. Adv. Funct. Mat. (2013), submitted
.
112
Stabilization of colloids by addition of salt
Sela Samin1, Yoav Tsori
2
1 Department of Chemical Engineering, Ben Gurion University of the Negev, Israel. [email protected]
2 Department of Chemical Engineering, Ben Gurion University of the Negev, Israel. [email protected]
We calculate the interaction potential between two colloids immersed in aqueous mixtures. We
calculate the effective interaction due to the combination of preferential solvent adsorption at the
colloids' surface and preferential ion solvation. The ion-specific interaction strongly depends on the
amount of salt added as well as on the mixture composition. We show that contrary to the classical
DLVO behavior, neutral or even charged colloids can be stabilized by addition of salt. The theory is
supported by experiments.
1 Samin, S., Tsori, Y. (2012): The interaction between colloids in polar mixtures above Tc. CJ. Chem. Phys. 136, 154908.
2 Samin, S., Tsori, Y. (2011): Attraction between like-charge surfaces in polar mixtures. EPL 95, 36002.
113
Photocatalytic activity of nanocomposite based on polyaniline and TiO2
nanoparticles
Zoran Šaponjić1, Marija Radoičić
1, ordana Ćirić-Marjanović
2, Mirjana Čomor
1
1Vinča Institute of Nuclear Sciences, University of Belgrade, Belgrade, Serbia, [email protected]
2Faculty of Physical Chemistry, University of Belgrade, Belgrade, Serbia
During recent decades, photocatalysis has attracted much attention as an emerging successful
technology for purifying wastewater from industries and households. TiO2 is one of the most
investigated semiconductors in the field of photocatalytic degradation of pollutants due to chemical
stability, adsorption capability and photocatalytic efficacy for decomposition of organic compounds in
air and water. The wide band gap of TiO2 (3.2 eV) allows it to absorb the photons of ultraviolet light
that occupies only small fraction of solar spectrum, which limits its wider use. One of the possible
ways to utilize the broader part of the solar spectrum is sensitization of TiO2 with suitable sensitizer
[1]. High absorption coefficients in the visible part of the spectrum, high mobility of charge carriers
(consequence of presence of extend p-conjugated electron systems) and good environmental stability
of conductive polymers make them a good choice for TiO2 sensitization. Moreover, many conductive
polymers in their doped or undoped states are efficient electron donors and good hole transporters
upon visible light excitation [2]. The subject of this work was in situ synthesis and characterization of
Polyaniline (PANI)/TiO2. Its potential applicability as photocatalyst was checked using a typical
photodegradation reaction of Rhodamine B (RB) in a suspension. RB is a stable organic dye
occasionally used as a model compound for estimation of activity of TiO2 based photocatalysts, in
reactions of photodegradation. PANI/TiO2 nanocomposite was synthesized by the oxidative
polymerization of aniline with ammonium peroxydisulfate in water, in the presence of colloidal TiO2
nanoparticles of an average diameter of 5 nm. The resulting nanocomposite powder was used for
photocatalytic degradation of RB. Its photocatalytic activity has been compared with activity of neat
colloidal TiO2 nanoparticles. Obtained nanocomposite has enhanced absorption in visible part of
spectrum and showed higher efficacy toward discoloration of RB compared to bare TiO2.
1 X. Chen, S. Mao, Chem. Rev., (2007), 107 2891-2959. 2 X. li, D. Wang, G. Cheng, Q. Luo, J. An, Y. Wang, (2008), App. Catal. B: Environ. 81 (2008) 267-273.
114
Growth, sliding and detachment of a bubble near a wall:
effect of the wetting conditions
Julien Sebilleau
1, Catherine Colin
1
1Institut de Mécanique des Fluides de Toulouse, INPT, UPS, CNRS, Toulouse, France, [email protected]
The growth and departure of bubbles nucleated on a wall are of particular interest in industrial
situations such as the gas/liquid contactors in chemical processing, vapor nucleation in evaporators or
inkjet printing devices. In most of these industrial configurations, the bubble grows in a shear flow
and most of the studies1,2
aims to predict the radius of bubble when it detaches from a force balance
analysis. Such an approach appears to be limited by the modeling of the capillary term and more
precisely by the modeling of the contact angle hysteresis.
In this presentation, we will first show the necessity to take into account the effect of the
contact angle hysteresis to improve the prediction of the bubble radius at departure. Then we will
present some experimental results on the sliding and detachment of a gas bubble nucleated under an
incline. The substrate is a Teflon plate ensuring a high contact angle (r=63° and a=107°) and a large
hysteresis (~44°) for the liquid used (water). Results of the measurement of the maximal stable
volume of the bubble with respect to the inclination angle and comparison with theory will be first
given. Then some aspect of the sliding of the bubble and its detachment will be presented
Sliding and detachment of a bubble on a Teflon wall.
1Klausner J.F., Mei R., Bernhard D.M., Zeng L.Z. (1993): Vapor bubble departure in forced convection boiling. Int. J. Heat
Mass Transfer 36, 651-662.
2 Yoshikawa H.N., Colin C (2010): Single vapor bubble behavior in a shear flow in microgravity Int. Conf. on Multiphase
Flows, Tampa USA June 2010.
115
Dynamics of three phase contact lines of evaporating nanofluid droplets
Khellil Sefiane1, Martin E.R. Shanahan
2, Daniel Orejon
1
1 School of Engineering, The University of Edinburgh, Edinburgh EH9 3JL, UK, [email protected]
2 niversité de Bordeaux, nstitut de Mécanique et d’ ngénierie-Bordeaux, France, [email protected]
We describe an experimental investigation of the concomitant evaporation and (de)wetting behavior
of sessile drops of ethanol, either pure, or containing small amounts of titanium oxide nanoparticles.
Pure ethanol behaved in a more or less “ideal” manner, with constantly decreasing contact radius, at
essentially constant contact angle. However, distinct “stick−slip” pinning behavior of the triple line
occurred when nanoparticles were added to the base liquid. Increased nanoparticle concentration
enhanced the “stick−slip” behavior. The observed behavior is attributed to the effects of particle
accumulation near the contact line, caused by the now-established advective flow during evaporation.
“Slip” behavior can be explained by hysteretic energy barriers, somewhat akin to line tension. The
“stick” behavior was not complete: some triple line drift occurred (“pseudo-pinning”). t is postulated
that this may be due to small-scale pinning of the triple line by deposited particles, or to increased
effective viscosity due to high, local nanoparticle concentrations.
Furthermore, the dynamics of the three phase contact line for water and ethanol is
experimentally investigated using substrates of various hydrophobicities. Different evolution of the
droplet profile is found to be dependent on the hydrophobicity of the substrate. A simple theoretical
approach based on the unbalanced Young force is used to explain depinning of the contact line on
hydrophilic surfaces or the monotonic slip on hydrophobic substrates. A second part to the work
involves the addition of different quantities of titanium oxide nanoparticles to water and a comparison
of the evaporative behaviour of these novel fluids with the base liquid (water) on substrates varying in
hydrophobicity i.e. silicon, Cytop® and PTFE is presented. Stick-slip behaviour observed is found to
be dependent on nanoparticle concentration. Evaporation rate is closely related to the dynamics of the
contact line. These findings may have an important impact when considering evaporation of droplets
on different substrates and/or containing nanoparticles.
1 Orejon D., Sefiane K., and Shanahan M.E.R. (2011): Stick–Slip of Evaporating Droplets: Substrate Hydrophobicity and
Nanoparticle Concentration. Langmuir 27, 12834–12843.
2 Moffat J.R., Sefiane K., Shanahan M.E.R., and (2009): Effect of TiO2 Nanoparticles on Contact Line Stick−Slip Behavior
of Volatile Drops. J. Phys. Chem. B 113 8860–8866.
116
Structure of “coffee-ring” nano-deposits following drop evaporation
Martin E. R. Shanahan1, Alexandros Askounis
2,Vasileios Koutsos
2, Khellil Sefiane
2
1 Univ. Bordeaux, CNRS, Arts et Metiers ParisTech, I2M, UMR 5295, F-33400 Talence, France,
[email protected] 2 Institute for Materials and Processes, School of Engineering, The University of Edinburgh, King’s Buildings, Mayfield
Road, Edinburgh, EH9 3JL, United Kingdom.
[email protected] , [email protected] , [email protected]
Sessile drops of a monodisperse nano-suspension (SiO2 in water) were found to evaporate
following a stick-slip regime1 of the three-phase contact line, i.e. immobility of the triple line followed
by rapid recession, the cycle being repeated. “Coffee-ring” deposits remained after full evaporation,
corresponding to the “stick” phases. Examination revealed an unexpected, disordered region formed
at the exterior edge of the closely-packed nanocolloidal crystalline structure. To assess the role of
advective particle velocity, during evaporation, on particle structuring, experiments in reduced
pressure environments were undertaken. Lower pressures invoke higher evaporation rate and
consequently advective speed. Such experiments revealed the promotion of hexagonal packing at the
very edge of the crystallite with increasing velocity2. Quantification of particle velocity and
comparison with measured deposit shape for each case allowed us to provide a tentative description of
underlying mechanisms governing nanoparticle deposition. Behaviour is governed by the interplay
between fluid, and hence particle, flow velocities (the main ordering parameter) and wedge
constraints and disjoining pressure (the main disordering parameter). Furthermore, the formation of a
second, disordered region of particles at the interior edge of the deposit (towards the bulk fluid) was
found and attributed to the rapid motion of the triple line during the “slip” regime. Additionally, the
magnitude of the pinning forces acting on the triple line of the same drops was calculated. These
findings provide further insight into the mechanisms of the phenomenon and could facilitate its
exploitation in various nanotechnological applications.
(a) Micrograph of coffee-stain left after evaporation of aqueous suspension drop containing 0.125% wt. SiO2 nanoparticles.
(b) Evolution of contact angle (squares) and contact radius (triangles) for same drop.
1 Moffat J.R., Sefiane K., Shanahan M.E.R. (2009): Effect of TiO2 Nanoparticles on Contact Line Stick−Slip Behavior of
Volatile Drops. J. Phys. Chem. B 113 8860–8866.
2 Askounis A., Sefiane A., Koutsos V., Shanahan M.E.R. (2013): Structural Transitions at a Ring-Stain Created at the
Contact Line of Evaporating Nano-Suspension Sessile Drops. Phys. Rev. E (in press).
117
Added mass coefficients of bubbles near gas-liquid interface and of
ellipsoidal bubble pairs by CFD simulations
Miroslav Simcik, Marek Ruzicka
Institute of chemical process fundamentals, Czech academy of sciences, Prague, Czech republic, [email protected]
The added mass coefficient C was calculated for bubbles in different flow situations using the
volume of fluid (VOF) model. The full non-stationary 3D model equations were solved numerically
using CFD over small initial time interval in order to obtain the information about the bubble initial
acceleration from which the added mass coefficient of the bubble(s) can be calculated. The
methodology was described in detail in our paper [1]. Several geometrical configurations were
considered, which are physically relevant and difficult to treat analytically. We studied a single or
multiple spherical and ellipsoidal bubble(s) near boundaries or in different spatial configurations. The
effect of the key control parameters (bubble aspect ratio, dimensionless distances) on the added mass
coefficient is presented. Easy-to-use closed formulas (correlations) are provided for the values of C,
where possible.
1M. Simcik, M.C. Ruzicka, J. Drahoš, Computing the added mass of dispersed particles, Chemical Engineering
Science, Volume 63, Issue 18, September 2008, Pages 4580-4595.
118
Evaporation and adsorption of drops on solid and porous substrates
D. Siregar1, J.G.M. Kuerten
1, Cees v.d. Geld
1
1Faculty of Mech. Eng., Eindhoven University of Technology, The Netherlands, [email protected],
This presentation compares the results of a new numerical model for drops on permeable and
porous substrates with experiments. The model describes the dynamics of the solvent, the evaporation
process at the drop-air interface, the convective-diffusive transport of the solute molecules and the
adsorption of the solute particles onto or within the substrate. For the absorption of the droplet, the
flow within the porous medium is described by Darcy's law and driven by the capillary pressure. The
concentration of the solute particles is controlled by convective and diffusive transport and depends
on the local rates of evaporation, the rates of absorption on and in the substrate and possibly on
mechanisms occurring in the precursor film, if present. Due to their non-linearity, the governing
equations have to be solved numerically. The spatial derivatives are discretized using a finite volume
method. Time integration is performed with a combination of a fifth-order accurate Gear method and
a first-order accurate implicit Euler method. A sensitivity analysis is performed by variation of
physical properties and an accuracy analysis on the numerical approach is carried out.
Two useful experimental results without adsorption were reported in the literature and the
model has been validated by comparison to experimental results concerning drop mass loss rate and
contact angle histories. Well-known coffee-stain rings are found to occur due to convection in the
drop while inhomogeneous evaporation at the drop interface enhances the effect. In the case where a
precursor film was proven to exist, differences in mass loss rates are explained with the Kelvin effect.
In spite of the uncertainty of adsorption parameters also the penetration depth and absorbed volume in
a porous medium compares well with experimental results from literature.
119
Thermoresponsive PNIPAM-g-PEO nanoparticles for delivery of
NSAIDs
Borislav Soklev, Elena Mileva, Dimi Arabadzhieva
Department of Interfaces and Colloids, Institute of Physical Chemistry,
Bulgarian Academy of Science, Sofia 1113, Bulgaria,
e-mail: [email protected]
Core-shell nanoparticles from thermally-responsive biocompatible graft PNIPAM-g-PEO
copolymers can incorporate NSAID indomethacin at room temperature and release the drug under
controlled conditions at 37 oC. The aim of the present investigation is to clarify the mechanisms of
inclusion and discharge processes.
Extensive studies are performed on dynamic, equilibrium and rheological properties of the
adsorption layers of aqueous polymer solutions at the air/solution interface. The investigated systems
contain various ethanol quantities. Copolymers with different degrees of grafting are probed.
Additional information is acquired from measurements of surface forces by the microinterferometric
foam-film techniques, equipped with Scheludko-Exerowa cell.
The obtained results provide valuable input about indomethacin entrapment and release
mechanisms by the PNIPAM-g-PEO nanoparticles. These data supply important knowledge about
fine-tuning of drug uptake and release by core-shell nanoparticles. The investigations give grounds for
certain generalizations about the optimization of the nanoparticles’ design and their more efficient
functionalization in view of both the targeted and similar NSAID systems.
Acknowledgements:
The financial support of NSF of the Ministry of Education, Youth and Science (Bulgaria) by
Projects М 03/137 and B 051PO001–3.3.06–0038 are gratefully acknowledged.
120
Atomization of biocolloids:
a perspective for regenerative inhalation therapy?
Tomasz R. Sosnowski, Anita Kurowska
Faculty of Chemical and Process Engineering, Warsaw University of Technology, Warsaw; [email protected]
Proper lung function is dependent on its huge surface area which must be open and available
for the gas-exchange. In case of damage of the cellular ultrastructure (e.g., by burning, inhaling
caustics or irritants) it may be hypothesized that lost functions of some regions of the lungs can be
restored by regenerative medicine approach, i.e. by seeding of cells with progenitor (precursor)
potential1. The idea of presented research is related to a possible application of biocolloidal aerosol as
a carrier of living cells.
The classical inhalation therapy consists in delivery of medicines as aerosol targeted directly to
the respiratory system. By this method, local action of inhaled material is achieved (important issue in
asthma, COPD and lung infections) but also the systemic absorption may be expected (it is useful e.g.,
for vaccination2). Here we tested various techniques of aerosol generation from biocolloids, i.e. liquid
systems containing living cells. Three types of model cells were selected to assess the stress-
dependent effects on biological activity during spraying in different types of medical atomizers
(nebulizers): pneumatic, ultrasonic, vibrating-mesh and mechanical devices (nasal spray pumps and
PennCentury Microsprayer). Cell integrity and survival have been tested by several bioassays,
selected suitably to the biological entities used. Aerosol size distribution was measured with a
diffraction spectrometer (Malvern Spraytec).
The results of the study indicate that atomization techniques used in classical aerosol therapy
are unsuitable for spraying of living cells due to very high hydrodynamic stresses (Fig.1). On the
other hand, mechanical spraying (e.g., by Microsprayer device) allow to obtain aerosol with almost
intact cells (survival rate above 90%), however the average droplet size obtained is an order of
magnitude higher than produced in nebulizers. This factor sets limitations for using these aerosols for
cell delivery into deep lungs because of poor penetration of large droplets via tracheobronchial tree.
1 Petersen T.H., Calle E.A., Niklason L.E. (2011): Strategies for Lung Regeneration. Materials Today 14, 196-201.
2 Tonnis W.F. et al. (2012): Pulmonary Vaccine Delivery:A Realistic Approach? J Aerosol Med Pulm Drug Del 25, 249-260.
Fig. 1. Model-bacteria cell inactivation during Fig.2. Size distribution of droplets emitted
atomization in a vibrating-mesh nebulizer from Microsprayer device.
Acknowledgements: Work supported by governmental funds for science in 2010-2013 (project no. NN 209 0233 39)
and done under umbrella of COST action MP1106.
121
Mg-C nanocomposites for hydrogen storage
Tony Spassov*,1
, Zlatina Zlatanova1, Eli Grigorova
2, Maya Spassova
1, Mitko Hristov
2
1Faculty of Chemistry and Pharmacy, niversity of Sofia “St.Kl.Ohridski”, 1 James Bourchier str. 1164 Sofia,
Bulgaria 2 Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, bl.11, Acad. G. Bonchev str., 1113 Sofia,
Bulgaria
Mg-C and MgH2-C nanocomposites are prepared by ball milling using different kinds of
carbon additives and magnesium with different particle size. The samples consist of 5-10 μm
Mg/MgH2 particles, surrounded and/or coated by carbon flakes. Mg and MgH2 in the as-milled
materials show nanocrystalline microstructure (50-100 nm), as the grain and particle size reduction,
caused by the milling, depends on the type of the carbon used for the composite production. High-
pressure DSC analysis shows that the hydriding process starts at about 200oC for all materials studied,
but the hydriding mechanism looks different for the composites with different kind of carbon additive,
supposed to play a catalytic role and protecting magnesium from oxidation. It was also found that the
incorporation of carbon into the surface of the MgH2/Mg particles creates high density of defects,
leading to the formation of easy accessible for hydrogen sites and enhances its diffusion into the
magnesium grains. The composites containing finer magnesium experience absorption capacity
deterioration with hydriding/dehydriding cycling, but for some of the carbon additives this worsening
is not so strong. More pronounced positive effect on the hydrogen sorption characteristics of
magnesium was found for these carbon additives, which provide better protection of the Mg surface
from oxidation and particles agglomeration during hydriding/dehydriding cycling. Possible
explanation of the improved dehydriding behavior of these composites, related to the fine particle and
grain size and better contact between the carbon and MgH2/Mg particles was proposed.
122
Hydrodynamic interactions of a bubble pair and bubbles in clusters
Petr Stanovsky, Marek Ruzicka
Department of Multiphase Reactors, Institute of Chemical Process Fundamentals ASCR,
Prague, Czech Republic, [email protected]
An arrangement of gas bubbles rising in line in a liquid (bubble chain) is natural geometric
configuration of them considering the common bubble formation at a capillary or an orifice. A pair of
bubbles rising in tandem then represents a structural unit of such system. The bubbles are often
sufficiently clean so free-slip condition apply at their surfaces and bubble rises with Reynolds number
of order 101 - 10
2 in low viscosity liquids.
We conducted the experiments with ultrapure water and silicon oils to explore dynamics of
these bubble configurations and to compare it with a theory1,2
. The three dimensional path of bubbles
during the rise was reconstructed from double side view using high-speed cameras. The influence of
particle separation and Reynolds number will be presented. Interestingly the small variance of bubble
sizes has shown to be responsible for a scatter of the data obtained in ultrapure water3. It should be
noted that an influence of surfactants on the structure of bubble aggregates and their stability remains
almost unexplored experimentally at the mesoscale so far.
1 Kok, J. B. W. (1993): Dynamics of a pair of a gas bubbles moving through liquid. Part I. Theory. Eur J Mech B -Fluids
12(4), 515-540.
2 Harper. J.F. (1997): Bubbles rising in line: why is the first approximation so bad? J Fluid Mech 351, 289-300.
3 Kumaran, V., Koch, D. L. (1994): The effect of hydrodynamic interactions on the average properties of bidisperse
suspension of high Reynolds number, low Weber number bubbles. Phys Fluids A 5(5), 1123-1134.
123
Measurement of temperature field in a droplet by Laser Induced
Fluorescence and by Fluorescence Lifetime Imaging Microscopy
Martin Still1, Tatiana Gambaryan-Roisman
1,2 and Peter Stephan
1,2
1Technische Universität Darmstadt, Institute of Technical Thermodynamics, Petersenstr. 17, Darmstadt, 64287, Germany
2Technische Universität Darmstadt, Center of Smart Interfaces, Petersenstr. 17, 64287 Darmstadt, Germany
E-mail: [email protected]
Droplet evaporation plays an important role in many technological applications including spray
cooling and inkjet printing. The temperature distribution inside the droplet and at the liquid-gas
interface significantly affects the evaporation rate and the thermocapillary flow in a droplet, hereby
influencing the deposit formation in the inkjet printing technology or cooling efficiency in the spray
cooling application.
Temperature measurement at the liquid-gas interface of a droplet is a challenging task,
especially when intrusive measurement techniques have to be avoided. In this work two non-intrusive
temperature measurement methods are applied and compared.
The first is the well-established Laser Induced Fluorescence (LIF) method, in which a
fluorescing dye is excited by a laser beam. The spectral intensity of the emission depends on
temperature. In the two-color/single-dye LIF, emitted light intensities at two different wavelengths
with different temperature sensitivities are compared with each other in order to extract the
temperature. Until now LIF has been used for measurement of average temperature over a spot of a
minimum size of 200 mm. We combine LIF with Confocal Laser Scanning Microscopy (LSM). This
combination allows scanning the temperature over the whole droplet volume with high spatial
resolution.
The second method is Fluorescence Lifetime Imaging Microscopy (FLIM). This technique
benefits form the dependence of the fluorescence lifetime of some dyes upon temperature. The dye is
excited by a pulsed laser. After excitation the duration of the luminescence of the dye is measured.
The duration is defined as the point, when the intensity reaches a certain threshold relative to the
intensity at excitation. Typically the decay follows an exponential function while the order of
magnitude for the lifetime is a few nanoseconds.
In our setup the lifetime is measured by the confocal laser scanning microscope pixel by pixel.
We use in our experiments the Kiton Red dye (Sulforhodamine B) for characterization of water
droplets. The Laser excitation wavelength is 404 nm.
Both non-intrusive methods are used in our work for measurement of the temperature inside
evaporating water droplets and at the liquid-gas interface. The advantages and disadvantages of both
methods are discussed.
124
Bubble bouncing with a free surface in hypergravity conditions
Francesc Suñol1, Ricard González-Cinca
1
1 Applied Physics Department, Universitat Politècnica de Catalunya, Barcelona, Spain, [email protected]
We report novel experimental observations of the effects of the gravity level on the bubble rise
and bouncing with a free surface. Experiments have been carried out at the Large Diameter Centrifuge
(LDC) at ESTEC, where gravity level was changed from 1g0 to 19g0, with g0 = 9.81 m/s². Millimetric
air bubbles are released from a nozzle and rise rectilinearly in ethanol until they collide with the free
surface. At this moment, the bubbles bounce a few times before coalescing. The bubble size is
determined in the detachment process at the nozzle by a competition between the surface tension and
the buoyancy force. We find that the bubble size decreases with the gravity level in very good
agreement with the simplified model. Ellipsoidal bubbles rising rectilinearly in ethanol with We >
3.75 have been observed, as opposed to Moore’s theory. The terminal velocity has been found to
increase with the gravity level, although at higher gravity bubbles are smaller. The dynamics of the
bubble center during the bouncing process can be approximated by a damped oscillator. The
frequency of bouncing process increases with the gravity level, in reasonable agreement with a
simplified model based on the assumption that the free surface acts as an elastic membrane, driven by
capillary and gravity forces.
125
Molecular mechanisms of nanoparticle-cell interaction:
physico/chemical properties determining membrane-dependent cell
signalling events
Ulrich Sydlik1, Henrike Peuschel
2, Daniel Stöckmann
1, Christiane Bieschke
1, Andrea
Autengruber1, Marijan otić
3, Susanne Grether-Beck
1, Klaus Unfried
1
1IUF Leibniz Institute for Environmental Medicine, Düsseldorf, Germany; [email protected]
2INM Leibniz Institute for New Materials, Saarbrücken, Germany 3 nstitute Ruđer Bošković, Zagreb, Croatia
Investigating the molecular mechanisms of the interaction of nanoparticles with living cells is of
particular interest with respect to nanomedical and biotechnological aspects. But also, with the
growing importance of nanotechnology the probability of an unintended human exposure against
nanomaterials is exponentially increasing. In addition to directly cytotoxic effects, subacute reactions
like apoptosis, proliferation and inflammation may contribute to the toxicity of these materials (1).
Using carbonaceous particles of different size classes, in our previous studies we identified the
initial molecular steps of sub-acute toxic effects of nanoparticles in different types of epithelial cells
(2). Molecular analyses of membrane compartments of alveolar lung cells demonstrate that carbon
nanoparticles in lung epithelial cell induce changes in the lipid composition of lipid raft signalling
platforms. These molecular events are triggering the ligand-independent activation of the surface
receptor EGF-R (epidermal growth factor receptor). Intervention experiments using antioxidants but
also biophysically active 'compatible solutes' demonstrate that the nanoparticle-specific generation of
oxidative stress is the initial event of the observed adverse effect and these events can be prevented by
stabilization of lipid rafts and macromolecules located within the signalling platforms (3). Using a set
of poorly soluble nanoparticles and their non-nano counterparts, we were able to establish an in vitro
cell-based test battery which we suggest as early screening method for the safety of nanomaterials.
Currently the system is evaluated for modern metal-based nanoparticles which are designed for
diagnostic and therapeutic applications in humans. Interestingly, in addition to the capability to trigger
oxidative stress properties including particle shape appear to modify the molecular events occurring
during nanoparticle cell interaction.
1
Unfried K, Albrecht C, Klotz L-O, von Mikecz A, Grether-Beck S, Schins RPF. (2007) Cellular responses to
nanoparticles: target structures and mechanisms. Nanotoxicol 1:1-20. 2
Peuschel H, Sydlik U, Haendeler J, Büchner N, Stöckmann D, Kroker M, Wirth R, Brock W, Unfried K. (2010) c-Src-
mediated activation of Erk1/2 is a reaction of epithelial cells to carbon nanoparticle treatment and may be a target for a
molecular strategy. Biol Chem 391:1327-1332. 3
Peuschel H, Sydlik U, Grether-Beck S, Felsner I, Stöckmann D, Jakob S, Kroker M, Haendeler J, Gotić M, Krutmann J,
Unfried K. (2012) Carbon nanoparticles induce ceramide- and lipid raft-dependent signalling in lung epithelial cells: a
target for apreventive strategy against environmentally-induced lung inflammation. Part Fibre Toxicol in press
(doi:10.1186/1743-8977-9-48).
126
Microbubble contrast agents in ultrasound imaging and therapy
Meng-Xing Tang
1* and Robert J Eckersley
2
1 Department of Bioengineering, Imperial College London, London, U.K., [email protected]
2 Department of Biomedical Engineering, King’s College London, London, .K.
Ultrasound imaging is one of the most routinely used clinical imaging tool for medical
diagnosis. Comparing with other modalities it is non-ionizing, real-time, far more accessible and low
cost. The advent of microbubble contrast agents has opened up exciting possibilities of obtaining
quantitative information relating to tissue vascularity, tissue perfusion and even endothelial wall
function. Furthermore it has been shown that microbubbles can be used, together with ultrasound, to
facilitate drug and gene delivery. In this presentation we will introduce the microbubbles, how they
interact with ultrasound, why they are useful and future opportunities and challenges.
A microbubble is a gas bubble typically consists of an inert gas core stabilized by lipid,
albumin or polymer coating. Microbubbles are microns in size and are small enough to pass
pulmonary circulation. Due to the coincidence of the resonance frequency of these micron-sized
bubbles being within the diagnosictic ultrasound frequency range, they have become established as
the most effective form of contrast agent available for ultrasound imaging [1].
Significant technical advance has been made in the past decade in the fabrication of the
bubbles, measurement and modeling of their acoustic behavior, and their imaging with ultrasound.
Currently ultrasound imaging system operating in the so-called contrast-specific mode is sensitive
enough to detect a single microbubble, making use of their unique nonlinear oscillation behavior
under ultrasound excitation.
Microbubbles have been increasingly used in a wide range of clinical and pre-clinical
applications. As the microbubbles flow with blood cells they provide an excellent means of
determining physiologically relevant microcirculation parameters from the contrast enhanced image
sequences. This has been investigated for a number of clinical conditions, notably the assessment of
myocardial function [2], diagnosis and treatment monitoring of tumours [3] and characterizing
atherosclerotic plaques[4]. Recent development of ultrasound molecular imaging promises highly
sensitive functional information and is revolutionizing the role that microbubbles and ultrasound can
play in clinical and pre-clinical applications [5] . Furthermore, microbubbles and ultrasound have
been used to help open up cell membranes and facilitate the delivery of therapeutic agents [6]. These
progresses will be described and future opportunities and challenges discussed.
1 Becher, H. and P.N. Burns, Handbook of Contrast Echocardiography. 1st ed. 2000, Berlin: Springer Verlag.
2 Porter, T.R. and F. Xie, Myocardial Perfusion Imaging With Contrast Ultrasound. Jacc-Cardiovascular Imaging, 2010.
3(2): p. 176-187.
3 Lassau, N., et al., Advanced Hepatocellular Carcinoma: Early Evaluation of Response to Bevacizumab Therapy at
Dynamic Contrast-enhanced US with Quantification-Preliminary Results. Radiology, 2011. 258(1): p. 291-300.
4 Feinstein, S.B., Contrast ultrasound imaging of the carotid artery vasa vasorum and atherosclerotic plaque
neovascularization. Journal Of the American College Of Cardiology, 2006. 48(2): p. 236-243.
5 Lindner, J.R., Molecular imaging of cardiovascular disease with contrast-enhanced ultrasonography. Nature Reviews
Cardiology, 2009. 6(7): p. 475-481.
6 Ferrara, K., R. Pollard, and M. Borden, Ultrasound microbubble contrast agents: Fundamentals and application to gene
and drug delivery. Annual Review of Biomedical Engineering, 2007. 9: p. 415-447.
127
Langmuir-Blodgett films of 2D metal oxide nanosheets as textured
crystalline interfaces
Johan E. ten Elshof1
1 MESA+ Institute for Nanotechnology, University of Twente, Enschede, Netherlands, [email protected]
Oxide nanosheets are the oxide equivalents of graphene. They have a thickness of ~1 nm and
can have lateral dimensions of over 50 m. Oxide nanosheets are made by exfoliation of layered
metal oxides in aqueous solution through a series of ion exchange processes. Both insulating and
semiconducting nanosheets can be made. We studied the mechanism of exfoliation and restacking of
lepidocrocite-type titanates into Ti0.87O2 nanosheets in solution by small angle x-ray scattering, and
developed a new method to monitor the kinetics of exfoliation by differential scanning calorimetry.
The resulting colloidal nanosheets are truly 2D single-crystal objects.
We optimized the conditions for Langmuir-Blodgett (LB) deposition of nanosheets to >99%
monolayer coverage on glass, silicon and PET. The resulting LB films present well-defined
microtextured crystalline surfaces that may be used for a variety of purposes: as crystalline interfaces
on amorphous substrates; for selective adsorption of ions or other species; in photocatalytic and other
electrochemical interface processes; or as crystalline templates onto which other materials can be
grown epitaxially. As an example of the latter, we show the growth of SrRuO3 on Ca2Nb3O10 and
Ti0.87O2 nanosheet LB films. Depending on nature of the nanosheet interface, [001] oriented films
grew on Ca2Nb3O10, and [110] oriented films on Ti0.87O2. The magnetic properties of SrRuO3 were
shown to be influenced by the underlying seed layer.
128
Hydrogen Storage and Supercapacitors
Steve Tennison
MAST Carbon International ltd. Jays Close, Viables, Basingstoke, RG22 4BA, UK. [email protected]
The use of nanoporous carbon has been widely investigated in essentially all energy storage
applications encompassing hydrogen storage, methane storage, supercapacitors, fuel cells and Li-ion
batteries. Common constraints in much of this work relate to the purity of the carbons used, their
reproducibility, the control of the pore structure and the physical form of the materials. Phenolic resin
derived nanoporous carbons have now been developed where all of these parameters can be readily
controlled. These have been investigated in
cryogenic hydrogen storage where they have been
used as a stable baseline material for round robin
and other test development studies1,2. They have
also shown good storage capacity (2.5% wt)
despite relatively low surface areas (810m2/g)
which might be attributable to the pore structure
which is centered at ~7nm which many papers
suggest is the optimum for cryogenic storage.
The materials have also been evaluated in both aqueous3 and non aqueous supercapacitors.
Operating in propylene carbonate4 it has been shown that the presence of controlled size and volume
micro and transport pores leads to a major improvement in both energy and power density. A
common feature of the carbon materials required for all of these applications is that the production of
materials with very high surface areas and pore volumes does not provide the best solution. The
applications are invariably constrained by the system volume and the more critical parameter is the
available area, or pore volume, per unit volume. In the case of gas storage, whether hydrogen or
methane, the minimization of the free volume is also critical. The production of controlled structure
materials that can meet both electrical thermal conductivity requirements will be discussed.
1 A Hruzewizz-Kolodziejczyk, C Ting, N Bimbo, T Mays, Int.Jnl.Hydrogen Energy, 37(2012) 2728 2 N Bimbo, V Ting, J Sharp, T Mays Colloids and Surfaces A, in press 2012 3 J A Fernandex, S Tennison, O Kozynchenko, F Rubiera, F Stoeckli, T A Centeno, Carbon, 47 (2009) 1598 4 C Lei, N Amini, F Markoulidis, P Wilson, S Tennison, C Lekakoua, jnl.Mat Chem A, In press (2013)
129
Patterned surface treatment by microplasmas to obtain
area selective wettability of surfaces
Michael Thomas1, Holger Gerdes
1, Marko Eichler
1, Claus-Peter Klages
1,2
1 Fraunhofer Institute for Surface Engineering and Thin Films IST, Braunschweig, Germany,
[email protected] 2 TU Braunschweig, Institut für Oberflächentechnik, Braunschweig, Germany
For biomedical and electronic applications like biosensors, flexible printed circuits, RFID
antennas and MEMS, patterned surfaces manufactured by subtractive processes based on lithography,
etching, or laser ablation are well established. Due to better cost and resource efficiency a new
additive process has been developed based on a novel patterning technology using plasma
functionalization or coating at atmospheric pressure, called plasma printing. In this process
microcavities with structure widths down to 10 µm are formed temporarily by contacting a substrate
with a suitably designed plasma stamp. Inside these microcavities partial discharges, special cases of
dielectric barrier discharges (DBDs), can be ignited for surface coating and modification processes in
a similar way as already demonstrated for common DBD arrangements.
Figure 1: Local plasma treatment at atmospheric pressure of a 100 mm diameter silicon wafer carrying a wet-chemically
etched topography with a height difference of 50 μm between recessed and elevated areas.
Depending on the application field, various adapted set-ups of the plasma printing technology
are possible. For surface functionalization of even non-flexible materials, like glass, wafers or thicker
polymer sheets, flat metallic or dielectric stamps with closed cavities were used. Area-selective
hydrophilic properties can so be achieved by plasma activation. Using nitrogen-containing
atmospheres more than 10 primary amino groups per nm2 can be introduced into polyolefine surfaces.
With these technologies moreover patterned chemical functional coatings with different
monomers, e.g. aminopropyl-trimethoxysilane, glycidylmethacrylate or acetylene, has successfully
been demonstrated for structure widths down to 50 µm. Moreover (super-) hydrophobic patterns can
be achieved using multilayer coatings using silanes or fluorocarbon based monomers.
Selective treatment of porous materials like foams, non-wovens or textiles is possible. First
experiments with superhydrophobic polyester-based textile material show that it is possible to obtain
area-selective hydrophilizations with high resolutions down to 50 µm. The plasma treatment may be
controlled such that back side of the textile remains superhydrophobic, thus e.g. preventing
penetration of adhesives or dyes1.
1 Thomas, M. et al. (2012): Plasma Printing and Related Techniques – Patterning of Surfaces Using Microplasmas at
Atmospheric Pressure. Plasma Process. Polym. 9, 1086-1103.
130
Wall Shear Stress Induced by Taylor Bubbles in Inclined Flow Channels
Jaroslav Tihon , Věra Pěnkavová, Jiří Vejražka
Institute of Chemical Process Fundamentals, Rozvojová 135, 16502 Prague, Czech Republic
The motion of single air bubbles in flat channels is experimentally investigated. The
electrodiffusion technique of near-wall flow diagnostics is applied to measure the wall shear stress
distribution under large rising bubbles. The measurements are synchronized with the visual
observation of bubble movement by a high-speed camera. The analysis of video records provides
information on the bubble shape and terminal velocity. The experiments are carried out for three
different channel configuration (with heights of 1.5, 4, and 8 mm), cover a wide range of channel
inclination angles (from horizontal to vertical position), and dealing with both the bubbles in stagnant
and in co-flowing water. The directionally sensitive, two-strip electrodiffusion probe is proved to be
an effective tool to investigate the near-wall flow response to translating bubbles. It provides
information not only on the wall shear rate distribution, but also detects the location of near-wall flow
reversal, gives an estimate of the thickness of liquid film separating the large bubble from the wall,
and provides also the characteristics of capillary waves appearing in the bubble tail region. The effect
of channel inclination angle on the modification of wall shear stress distribution along the upper and
bottom wall is also discussed.
131
A model system for foam fractionation
ST Tobin1,*
, S Hutzler1, AJ Meagher
1, A Marguerite
1, D Weaire
1
1 School of Physics, Trinity College Dublin, Ireland
* Corresponding author: [email protected]
Foam fractionation is an industrial process in which compounds with different surface activities
are separated using foam. We present a model system relevant to this process, consisting of foam
moving through an inverted U-tube connecting two reservoirs of surfactant solution. The Foam
Drainage Equation [1] is used as the basis for a theoretical analysis of this process. Exact analytical
formulas for key properties of the system may be found in the limit of infinite leg length and zero
bend length. Numerical calculations and experiments were conducted and support the main theoretical
results [2].
1Verbist, G., Weaire, D. & Kraynik, A (1996): The foam drainage equation. Journal of Physics: Condensed Matter 8, 3715–
3732.
2 Hutzler, S., Tobin, ST., Meagher, AJ., Margeurite, A. & Weaire, D. (2013): A model system for foam fractionation.
Submitted.
132
Modeling of Three Phase Flow by Incompressible Smoothed Particle
Hydrodynamics
Nima Tofighi1, Mehmet Yildiz
1
1 Faculty of Engineering and Natural Sciences, Advanced Composites and Polymer Processing Laboratory, Sabanci
University, Turkey, [email protected]
In this study, a two dimensional Incompressible Smoothed Particle Hydrodynamics (ISPH)
method for modeling incompressible, immiscible three phase fluid flows has been developed. Surface
tension coefficients are decomposed into phase specific coefficients and surface tension force is
exerted by implementing continuum surface force (CSF) model. To complement this, a unique color
function is associated with each phase and then smoothed out to improve the robustness of the method
while a threshold has been implemented for choosing reliable normals to increase the accuracy of
computed surface tension force. Furthermore, artificial particle displacement has been employed to
ensure uniform spread of particles throughout the computational domain. Several test cases have been
simulated to ensure the capability of the method in handling various three phase flow combinations.
Having an analytical solution, the formation of a lens shape from a circular droplet under
surface tension forces has been studied to facilitate testing the accuracy of the proposed method.
Results show that this test case is highly sensitive to initial particle positioning, favoring an
arrangement obtained from two phase diamond droplet relaxation over a droplet simply carved out of
an equally spaced particle arrangement. Simulations have been carried out in three different
resolutions, revealing that an abrupt cut at the tip of the lens is responsible for the inaccuracies
incurred at low resolutions. The results obtained from high resolution simulations at different surface
tension ratios using improved initial condition are found to be compatible with analytical solution of
the equilibrium lens length. To further test the capabilities of the proposed method in handling
dynamic problems, a droplet levitation test case has been simulated for different surface tension
ratios. It is observed that, higher surface tension ratios result in faster break up from surface due to
larger force exerted at triple junction. Furthermore, higher surface tension ratio resulted in larger
maximum droplet velocity and higher stopping height. As the last test case, droplet spreading with a
contact angle of 90◦ has been considered. With minor modifications, the method has been able to
simulate contact line dynamics for a variety of Eotvos (Eo) numbers, demonstrating the flexibility of
the method and its capability in handling density and viscosity differences between phases. Results
obtained for Eo << 1 and Eo >> 1 are compatible with analytical results available for these two
extremes while a transition form spherical cap to puddle shape occurs for Eo values in between. The
simulations conducted and the comparison of the results show that the proposed ISPH method is
capable of handling different three phase flow problems common to many natural phenomena and
engineering problems.
133
Hybrid metal-organic framework structures studied by advanced
transmission electron microscopy
Stuart Turner1, Christian Wiktor
2, Roland A. Fischer and Gustaaf Van Tendeloo
1
1EMAT, University of Antwerp, B-2020 Antwerp, Belgium, [email protected]
2 Anorganische Chemie II, Ruhr-Universität Bochum, Universitätsstrasse 150, D-44780, Germany
Metal-organic frameworks (MOFs) consist of metal ion centers linked to by organic linkers to
create crystalline porous networks. In recent years, MOFs have received much attention because of
their high specific surface areas and pore volumes, applicable in gas (H2) storage, catalysis, and
photovoltaics.1
Also, many types of MOF crystals can be loaded with catalytically active materials
like Pd, Au, Cu and Ru in the form of nanoparticles, leading to a heightened activity in e.g. olefin
hydrogenolysis and methanol synthesis or with semiconductor nanomaterials like GaN or ZnO for
improved optical properties.2
Characterizing these delicate materials is far from trivial. Most of the common characterization
techniques like X-ray diffraction of nitrogen adsorption for this type of materials offer global
information only. However, in the case of nanostructured and/or -sized systems or upon loading with
nanoparticles, local structure information is of pivotal importance. Transmission electron microscopy
(TEM) is ideally suited for this, as it can provide structural information down to atomic resolution.
However, MOFs can be considered as soft matter and are very sensitive to electron beam illumination,
making TEM investigation of MOFs challenging. In the first TEM on MOF study, the relatively stable
pores of MIL-101 (Cr) were imaged intact.3 Improved TEM technology allows pore imaging of far
less stable MOFs like MOF-5 and ZIF-8 nowadays.4 Advanced TEM techniques like tomography
make it possible to determine the distribution of the nanoparticles within the MOF framework.
Combining imaging with spectroscopy in the electron microscope allows distinguishing between
chemical species within the frameworks and measuring bonding at the local scale.1
This presentation is intended to illustrate the potential of modern TEM as a characterization
technique for MOFs and nanoparticle-loaded MOFs, as well as for other types of (porous) soft matter.
1Turner S. et al. (2008): Direct imaging of loaded metal - organic framework materials (Metal@MOF-5). Chemistry of
Materials, 20, 5622-5627.
2Esken D. et al. (2011): GaN@ZIF-8: Selective Formation of Gallium Nitride Quantum Dots inside a Zinc
Methylimidazolate Framework. JACS, 133, 16370-16373.
3Lebedev O. . et al. (2005): First direct imaging of giant pores of the metal−organic framework M L-101. Chemistry of
Materials, 17, 6525-6527.
4Wiktor C. et al. (2012) Imaging of intact MOF-5 nanocrystals by advanced TEM at liquid nitrogen temperature.
Microporous and Mesoporous Materials, 162 131-135.
134
Design rules of swirl nozzles for steam attemperation
Dennis van Banning1, Cees v.d. Geld
1, Pieter Broos
2, Martin-Jan Strebe
2
1Faculty of Mech. Eng., Eindhoven University of Technology, The Netherlands, [email protected]
2Pentair V&C, Heerle, The Netherlands, [email protected]
The precise control of the steam temperature is a critical element for safe and efficient plant
operation. The desuperheater takes care of this process, also called attemperation, by atomization of
directly injected water. The present research aims at design rules for the pressure swirl nozzles of
Pentair V&C.
Various spray characteristics are measured with LDA, High-speed video camera and a Malvern
Spraytec. Inlet water temperature has been varied up to 85°C. Four different nozzle types have been
examined.
The breakup length of the spray turns out to be well predicted by a correlation of Han et al.[1].
Also the spray angle is well predicted with a correlation given by Lefebvre [2]. To avoid the breakup
region of the spray, with a length of typically 5 mm, velocity measurements have been carried out at
15 mm from the nozzle. Variation of this position the range 10 to 20 mm yielded 5 % changes at
maximum. This is as expected since kinetic energy is practically conserved in the process, typically
only 1 to 2 % of the incoming energy is converted into surface energy, and drop inertia dominates
added mass. Drop size distributions have been measured at various distances from the nozzle. The
correlations produced in this study give spray conditions at about 25 mm downstream of the nozzle
for atomization in air. Vaporization in high-temperature steam is subject of future study.
1 Z. Han, Z., Fan L., Reitz, R. D. (1997), Multidimensional modeling of spray atomization and air-fuel mixing in a direct-
injection spark-ignition engine, SAE Technical Paper 970884, Society of Automotive Engineers, Warrendale.
2 Lefebvre, A.H. (1989), Atomization and sprays.
135
Stability of coffee-based foamed system: the Frappe Coffee
Evdoxia-M.Varka1, Thodoris D.Karapantsios
1, Luciano Navarini
2
1Dept. Chemistry, Aristotle University of Thessaloniki, University Box 116, 541 24, Thessaloniki, Greece
2illycaffè s.p.a., via Flavia 110, 34147 Trieste, Italy, [email protected]
Frappe coffee is an instant cold refreshment very popular in Greece and other Mediterranean
countries and with a growing interest in USA. An important feature of Frappe coffee is its foam lying
on top of the coffee liquid mixture. It is both esthetic and sensory reasons that require this foam to be
stable over approximately an hour which is a typical time for drinking this type of coffee.
Experiments are performed with two different types of instant coffee (100% Arabica freeze
dried/Commercial product) employing three sucrose proportions to adjust sweetness to usual drinking
standards (sweet, medium, bitter). Sucrose is a common carbohydrate sweetener which acts also as
foam stabilizer. Frappe coffee foam stability is registered by monitoring the liquid drainage out of the
foam volume with two simultaneous techniques: (i) electrical measurements (non-
intrusive/continuous) for the evolution of the local liquid fraction at a specific height in the foam and
(ii) volumetric measurements (non-intrusive/intermittent) for the evolution of the global liquid
fraction over the entire foam volume. Results of each technique are compared and discussed. To our
knowledge this is the first time that such measurements are performed to investigate this appreciated
coffee-based food system.
136
Inviscid oscillations of constrained bubbles and drops
Jiri Vejrazka1, Lucie Vobecká
1, Jaroslav Tihon
1
1 Institute of Chemical Process Fundamentals, Prague, Czech Republic, [email protected]
In the instruments for measurements of the interfacial elasticity and viscosity, shape oscillations
of the bubble or drop may occur when the drop is forced at higher frequencies. For better
understanding of these shape oscillations, a linear inviscid theory is developed using variational
principles (via Lagrange's equations and Lagrange's lambda-multipliers). The theory allows
determining eigenmodes (i.e. eigenfrequencies, eigenmode shapes and damping of eigenmode
oscillations), but also response of the bubble shape to a motion of its support or to volume variations.
Present theory covers also the cases previously analyzed by Strani and Sabetta1 and Bostwick and
Steen2. It can be applied to both bubbles and drops. Overall, the theory is flexible, as it can easily
adapt to any type of constraints, and compared to previous treatments, it is also easy and intuitive.
The theory prediction has been compared to experiments. Good agreement is found for the case
of small bubbles, which have spherical static shape. Experimental results for larger bubbles and drops
deviate from the theory, as a neck is formed. It is shown that this deviation correlates well with a ratio
of bubble volume to the volume at its detachment.
Figure: High-speed record of a ubble oscillating at a tip of capillary, a) D = 1.48 mm, bubble oscillates mostly at first
eigenmode, b) D = 1.19 mm, oscillates mostly at third eigenmode
1 Strani, M., Sabetta, F. (1984): Free vibrations of a drop in a partial contact with a solid support. J Fluid Mech 141, 233-
247.
2 Bostwick, J. B., Steen, P. H. (1995): Capillary oscillations of a constrained liquid drop. Phys Fluids 21, 032108.
137
Experimental analysis of high Weber number drop impacts onto
superhydrophobic surfaces
F. Villa1, C. Antonini
2, M. Marengo
1, Ilia V. Roisman
3
1Department of Engineering, University of Bergamo, Viale Marconi 5, 24044 Dalmine (BG), Italy, [email protected]
2Current address: Laboratory of Thermodynamics in Emerging Technologies, Mechanical and Process Engineering
Department, ETH Zürich, 8092 Zürich, Switzerland. 3Department of Fluid Mechanics and Aerodynamics, Technical University of Darmstadt, Petersenstrasse 30, 64287
Darmstadt, Germany.
This work allowed to study the drop impact on hydrophobic and superhydrophobic surfaces
with an innovative apparatus used to create drop, with different diameter, and accelerate them to a
target.
It is evaluated not also the outcome of the impact (deposition or rebound) but also the rebound
time, when rebound occur, and the maximum spreading, for different velocity impact (from 4 to 8
m/s) and drop diameters (from 0.98 to 1.78 mm).
A rebound map for impacts has been proposed. For superhydrophobic surfaces the effects of
drop diameter and impact weber number on rebound time are compared with correlation found in the
literature.
For hydrophobic surfaces, at highest velocity impact, an upper ‘probabilistic’ limit of no
rebound is evaluated.
138
Shape oscillations of bubbles in solutions of surface-active agents
Lucie Vobecká1, Jiří Vejražka
1, Jaroslav Tihon
1
1 Institute of Chemical Process Fundamentals, Prague, Czech Republic, [email protected]
The effect of surfactants on the shape oscillations of a bubble, which is attached at a tip of a
capillary, is studied. In the experiments, shape oscillations of a bubble are invoked by a motion of a
capillary, to which the bubble is injected. Decaying oscillations are recorded and their frequency and
damping are evaluated. By changing the excitation frequency, three lowest oscillation modes are
studied. Experiments were repeated in aqueous solution of several surfactants (terpineol, SDS, CTAB,
Triton X-100, Triton X-45) at various concentrations.
Generally, these features are observed: Initially a surfactant addition leads to an increase of the
oscillation frequency (though surface tension is decreasing); this effect can be attributed to the
increasing interfacial elasticity. The decay time of oscillation is strongly decreasing, as a consequence
of energy dissipation linked with Marangoni stresses. At a certain critical concentration, frequency
decreases abruptly and the decay time passes by a minimum. With further addition of surfactant,
frequency decreases, and the decay time slightly lengthens. Above critical micelle concentration, all
these parameters stabilize.
Interestingly, the critical concentration, at which frequency drop occurs, depends on mode
order. This clearly shows that the frequency drop and minimum decay time are not a consequence of
some abrupt change of interfacial properties, but are a consequence of some simpler phenomena,
which still need to be explained.
139
Drop on demand inkjet printing
Herman Wijshoff
Océ Technologies B.V., Venlo, the Netherlands, [email protected]
Inkjet technology has evolved into a technology which plays an important role in the graphical
printing industry and in many emerging new industrial and medical applications1. Also for Océ, inkjet
has become one of the main printing technologies for the near future. Our piezo inkjet technology has
unique capabilities due to its ability to deposit a wide variety of materials on all kind of substrates in
well-defined patterns. The requirements for the inkjet printing technology will increase. The near
future demands for the generation of adjustable small drop volumes, higher drop velocities, higher
drop repetition rates, low cost price, etc. The physics behind the chain of processes comprise (i) the
two-way coupling from the electrical to the mechanical domain through the piezo electric actuator, (ii)
the coupling to the acoustic domain inside the ink channels, and finally the coupling to the fluid
dynamic domain with free surface flow, i.e. (iii) the drop formation and (iv) the drop impact,
spreading and solidification. Especially with the many new materials, the control of the interaction of
the jetted fluid with the different types of substrates is crucial. Furthermore, (v) wetting of the nozzle
plate and (vi) air bubbles, which require the modeling of two-phase flow, can have a negative
influence on the printhead performance.
The drops coming out of the nozzle can be measured with all kind of optical techniques2. Single
drops can even be captured for further analysis. What is happening inside the printhead is much more
difficult to measure. The most important measurement uses the piezo actuator also as a sensor, which
is especially in the research on jetting stability an important capability. However, this measurement
gives only the average pressure inside the ink channels. Therefore, the modeling of the physical
phenomena is an essential part of the research3. Added to the measurements, the modeling reveals the
chain of processes, which lead to the final goal: firing droplets of ink at a very high rate with any
desired shape, size and velocity, and a reliability as high as possible. With controlling techniques the
performance of printhead can be optimized effectively4.
To comply with the increasing and diverging requirements for today’s inkjet technology, a
fundamental understanding of the underlying processes is very important. For that, we are already
collaboration with many academic groups in the Netherlands and we are looking for ways to expand
this network further.
1J. Korvink, P. Smith, and D.Y. Shin (2012): Inkjet-based micromanufacturing, AMNS series 9, Wiley-VCH (2012).
2A. van der Bos (2011): Air entrapment and drop formation in piezo inkjet printing, PhD Thesis University of Twente.
3H. Wijshoff (2010): The dynamics of the piezo inkjet printhead operation, Physics Reports 491, 77-177.
4R. Babuska, X. Bombois, P. van den Bosch, M. Ezzeldin, A. Khalate, S. Koekebakker, G. Scorletti, S. Weiland, H.
Wijshoff, R. Waarsing, and W. de Zeeuw (2013): Piezo printhead control: jetting any drop at any time, in T. Basten, R.
Hamberg, F. Reckers, and J. Verriet, Model-based design of adaptive embedded systems, Embedded Systems series 22,
Springer.
140
Multiscale analysis of gas absorption in liquids
C.Wylock, S. Dehaeck, D. Mikaelian, A. Larcy, P. Talbot, P. Colinet, B.Haut
TIPs, Université Libre de Bruxelles (ULB), Brussels, Belgium, [email protected]
One of the main research activities of the TIPs Laboratory is the development of theoretical,
numerical and experimental methods for the characterization of gas-liquid absorption in industrial
systems. This is a multi-scale problem: the analysis of phenomena at different scales and their
coupling is required to improve the design and the operation of these systems.
At the interface scale, an original experimental tool and a dedicated procedure for the
characterization of the chemical absorption of CO2 (see Fig. A) in various liquids has been
developed1. This tool is currently used in collaboration with industry for studying new generation
aqueous amine solutions2 for efficient CO2 capture and regeneration technologies.
At the inclusion scale, the coupling between mass transport phenomena and chemical reactions
during the absorption of a gas in a liquid has been characterized by direct numerical simulations,
considering bubbles3 and liquid droplets
4 (see Fig. B). A new experimental set up and a data post-
processing method for the characterization of the dynamics and the morphology of ellipsoidal
bubbles5 have also been developed (see Fig. C).
At the scale of the industrial system, the results obtained at the scale of the interface or at the
scale of the bubble have been used for the development of models aiming at the analysis or the
optimization of various processes such as ozonation6 and sodium bicarbonate production
7.
Fig. A
Fig. B
Fig. C
(a) Boundary layer development during the absorption of CO2 in a liquid, visualized by interferometry; (b) time
evolution of the Sherwood number of a liquid droplet falling in a gas; (c) sketch of the experimental set up and superposition
of post-processed images acquired during the rise of a bubble.
1Wylock, C., Dehaeck, S., Cartage, T., Colinet, P., Haut, B. (2011): Experimental study of gas-liquid mass transfer coupled
with chemical reactions by digital holographic interferometry. Chem Eng Sci 66, 3400-3412.
2Wylock, C., Dehaeck, S., Alonso Quintans, D., Colinet, P., Haut, B. (submitted for publication): CO2 absorption in aqueous
solution of N-hydroxyethylpiperazine: experimental characterization using interferometry and modeling. Chem Eng Sci.
3Wylock, C., Larcy, A., Colinet, P., Cartage, T., Haut, B. (2011): Direct numerical simulation of bubble-liquid mass transfer
coupled with chemical reactions: influence of bubble shape and interface contamination. Colloids Surfaces A -
Physicochem Eng Aspects 381, 130-138.
4Wylock, C., Colinet, P., Haut, B. (2012): Gas absorption into a spherical liquid droplet: numerical and theoretical study.
Chem Eng J 207-208, 851-864.
5Mikaelian, D., Larcy, A., Haut, B. (submitted for publication): A new experimental method to analyze the dynamics and the
morphology of bubbles in liquids. Application to ellipsoidal bubbles. Chem Eng Sci.
6Talbot, P., Martinelli, L., Talvy, S. L., Chauveheid, E., Haut, B. (2012): Ozone inactivation of resistant microorganisms:
Laboratory analysis and evaluation of the efficiency of plants. Water Research 46, 5893-5903.
8Haut, B., Cartage, T. (2005): Mathematical modelling of gas-liquid mass transfer rate in bubble columns operated in
heterogeneous regime. Chem Eng Sci 60, 5937-5944.
141
Foaming Emulsions
P. Yazhgur, Y. Yoshitake1, S. Heitkam
1, E. Rio
1, A. Saint-Jalmes
2, D. Langevin
1, A. Salonen
1
1 Laboratoire de Physique des Solides, CNRS- Université Paris Sud 11, Orsay, France, [email protected]
2 Institut de Physique de Rennes, CNRS – Université Rennes 1, Rennes, France
Foams made from emulsions are found in many industrial
products, where either they are purposefully created for reasons
of function and texture or they are an unwanted side product due
to the foaming of an emulsion during preparation or use.
Interestingly, depending on the volume fractions of the
components and on the type of surfactant and oil used,
emulsions can strongly increase the stability of foams or
decrease it. Although research has been conducted on emulsions
as anti-foams, their use as stabilising agents for foaming has so far been less explored.
We have studied model foam-emulsion systems using a single surfactant to stabilise both the oil
drops and the air bubbles. We observed changes from very unstable to long-lived foams. We found
that in the case of rather stable foams, the confinement of emulsion droplets in the network formed by
the bubbles plays an important role. In order to understand the role of confinement, we have studied
the behaviour of emulsions in capillary tubes (1D confinement). Interesting new effects have been
evidenced, related to creaming of emulsions under circular confinement. The relation between these
findings and the peculiar behaviour of foamed emulsions will be discussed.
1 Salonen, A., Lhermerout, R., Rio, E., Langevin, D., Saint-Jalmes, A. (2012): Dual gas and oil dispersions in water:
production and stability of foamulsion. Soft Matter 8, 699-706.
Figure 2. Emulsion droplets in foams.
142
Microporous Materials from Particle-Stabilised Liquid Foams
Dominika Zabiegaj, Eva Santini, Eduardo Guzmán, Michele Ferrari,
Vincenzo Buscaglia, Maria Teresa Buscaglia, Giorgio Battilana, Francesca Ravera, Libero Liggieri
CNR- stituto per l’Energetica e le nterfasi, enova, taly, l.liggieri ge.ieni.cnr.it
Solid foams have remarkable potentialities as structural or functional materials in a variety of
applications, such as shock dumping/absorbers, thermal and sound insulation, advanced filtration and
separation membranes, hot gas cleanup, CO2 and other pollutant adsorption, catalyst supports,
components of rechargeable lithium batteries and electrolytic capacitors.
The production of these microporous materials from particle-stabilized liquid foams (or
emulsions) represents an attractive route for cost reductions and energy saving. To this aim it is
however necessary to achieve an accurate control of the structure and stability of the foam during the
various phases of the processing.
We present here a study aimed at the production of solid foams with tailored structural and
chemical features, after drying and/or sintering of liquid foams stabilized by associations of ceramic
or carbonaceous nanoparticles with surfactants.
Beside optimizing the protocols adopted for the solid foam production, the interfacial properties
of the single particle-laden liquid interfacial layers have been characterized in order better
understanding their relation with the properties of the obtained foams as well as the definition of
“key” features of the NP-surfactant systems responsible for specific structural, morphological and
functional characteristics of the material.
Aknowledgements: National Research Council and Ministry of Industrial Development, National
Joint Research Programme “Clean Carbon”
Reference: Zabiegaj D., Santini E., Guzmán E.., Ferrari M., Liggieri L., Buscaglia V., Buscaglia M.T., Battilana
G., Ravera F. (2012): Nanoparticle laden interfacial layers and application to foams and solid foams. Submitted to
Colloids and Surfaces A.
Solid foam after processing of a liquid foam stabilised by Carbon Soot plus CTAB. image size= 2.2 x 3.1 mm.
143
Closing the cycle with hydrogen
Andreas Züttel1
1 EMPA Materials Science & Technology, Switzerland, [email protected]
The growing population and growing demand for resources, e.g. energy and materials, requires
a change of the economic system. The current economy was developed with the industrialization and
is based on the following steps: mining of the resources, fabrication of the products; the consumption
converts the products into garbage and finally deposition of the waste. This leads to a depletion of the
resources and a negative impact on the environment.
Fig. 1 The economic system established during the industrialization (the past 200 years) on the left hand side and the
future economic system based on a closed cycle.
The fossil fuels are the main source of energy in the current economic system. The reserves of
fossil fuels are limited and there combustion leads to an increase of the CO2 concentration in the
atmosphere. Furthermore, the world wide demand for fossil fuels is increasing with time and the
economy of the industrialized society entirely depends on the availability of the fossil fuels.
There are just two ways to close the cycle[1]: remove the carbon from the energy cycle and
introduce hydrogen as an energy carrier for the solar energy or to extract CO2 from the atmosphere
and to reduce it with hydrogen to synthetic fuels. An energy system based on hydrogen suffers from
the limited energy density in a hydrogen storage material. On the other hand, the extraction of CO2
from the atmosphere with the today known processes are energy demanding and requires a large
surface area. However, the production of hydrogen from renewable energy and the storage of
hydrogen, i.e. the reaction of hydrogen with a metals or CO2, leading to a high energy density material
are the crucial steps in the future energy system.
1 Züttel, Andreas Remhof, Arndt Borgschulte, Andreas Friedrichs, Oliver “Hydrogen: the future energy carrier”, Phil.
Trans. Royal Soc. A – Math. Phys. and Eng. Sci. 368 (2010), pp. 3329 - 3342
